In only 3 years from the first stereolithography product from 3D Systems the company has now launched its first office-sized machine no larger than an office photocopier.

Developed by 3D Systems in Valencia California the Actua 2100 is a 3D concept modeller no larger than a standard office photocopier. It allows designers to produce three-dimensional models direct from their CAD systems but in their own offices. The machine is now being introduced in the UK via Bix one of three companies promoting its technology in the UK. Prices are reportedly in the order of (UK pounds)40 0

The Actua 2100 which also operates noiselessly and can therefore sit comfortably alongside other office equipment takes advantage of new 3D printing techniques under development at MIT in the USA. In a dry process the model is built up in successive layers using black white or grey Thermojet material a specially developed thermopolymer to produce an accurate 3D model in a few hours. The material is delivered point by point data being converted and individual nozzles triggered via piezoelectric signals analogous to an inkjet printer. Models are produced by means of a raster-based 96 printing process which uses a cutting algorithm to build up the model in a process similar to inkjet or phase-change printing. As a typical example it would take about five hours to produce a model of cup and saucer.

A key element in the development of the machine was the compatibility of material and printing head. The material to be developed needed to have a low melting point and a low viscosity. At the same time it has to withstand high temperatures without burning up in the process. The material that was used was paraffin. Although the newly developed nozzle heads withstood the temperatures the material failed to solidify quickly enough. Eventually the Thermojet material was developed which can be heated to 120degC and solidifies immediately on contact with the existing surface.

Designed to complement other stereolithographic processes the Actua 2100 is finding early uses with manufacturers of domestic appliances and household goods. German chair manufacturer Scharf is using the machine to carry out studies of the ergonomics of armrests for office chairs.

The Allegro software supplied with the Actua 2100 displays a simple control panel on the CAD workstation allowing the designer to select the models to be built and the scale factor. The software checks the data and alerts the designer to any errors before building the requested models. Allegro can run on any commercial UNIX platform or under Windows NT. The software can be installed within the network on several PCs allowing access to the Actua 2100 from several terminals. The software also allows several copies or different designs to be edited from different terminals at the same time working with the same carrier plate.

Allegro positions the model in the build space and generates a support grid geometry. This is necessary to be able to remove the model more easily from the support plate after the work cycle has been completed. Undercuts and overhangs can be represented. The design space itself is 250 x 200 x 200mm. After completion the entire platform is removed together with the component The support grid geometry is removed using a glass brush.

Once the build request is submitted it is queued for modelling enabling the designer to work on other tasks while the model is being completed. So the day when designers can fax real models to one another as our own correspondent Griff forecast last year draws ever nearer!

• Bix Computer Applications
• Andrew Miller
• 0115 840 4060

April 1999

Bewildering was the array of objects that began to appear on the market four or five years ago. Desks with worktops that adjusted at the touch of a button, chairs in a wide assortment of shapes and sizes, storage systems that were positively extra- terrestrial, and an even more mind-boggling collection of “optional extras”.

The reason for all this activity was EC directive 90/270/EEC, governing the use of VDUs in the office. The guidelines that preceded it were so vague that manufacturers were put into the position of having to outguess the EC to safeguard their entire product ranges from becoming obsolete overnight.

Predictably, when the directive was published, it was by no means as extreme as people were expecting. What it did was ensure that companies investing in computer equipment also provided their staff with adequate and appropriate working areas to enable them to do their jobs properly. This is a particular issue for design and drawing offices, not least because the computer systems they use are often large. In the past, companies have sometimes been tempted to economise by installing computers on existing desking systems, and this has resulted in cramped, unproductive working conditions.

As with the majority of EC directives, this one is really common sense: for each computer or workstation, employers must provide a working area that has a sufficiently large, low-reflectance working surface to allow a flexible arrangement of the screen, keyboard, documents and related equipment. This has now been mandatory for all new furniture since January 1993, and from 1 January 1997, all office furniture that does not comply will have to go.

What has been the effect of the EC regulations? One result has been to make employers far more aware of the conditions in which their staff work. This is certainly in their own interests: eye strain, cricked necks and bad backs can severely reduce productivity. Companies are now far more prepared to install new furniture to house their computer systems than they were three years ago.

The effect on the furniture itself has been more subtle. Once manufacturers understood that the “all-singing, all-dancing” workstation was not what the EC regulations demanded, they began to concentrate on improving existing designs. There are distinct advantages to using a height-adjustable desk. However, the directive leaves it to individuals to decide what suits their individual needs.

One change is in the huge range of optional extras now available. Today, most suppliers offer cable trays, fixed and mobile pedestals, digitiser/menu tablet insets, processor cradles, arm and foot rests, screens and lighting systems.

The advent of the “intelligent building”, has by no means eliminated the problem of trailing wires. Cable ducting has long been available as an attachment to desking systems. The latest innovation is an elevating cable tray that fits into the rear of the desk, giving users access to wiring without having to clear their worktops first.

The main change, however, has been the increased emphasis on the “workstation” itself – the desk and its attachments. Having gone through a whole series of permutations, the furniture industry is now concentrating most of its efforts on this. Scientific design techniques are producing increased leg room and mobility. A wider range of finishes is available, with more attention to non-glare surfaces that minimise eye strain. Desks are also becoming larger: they are now available, not just in the standard 725mm, but in 850mm, 1 metre or even larger depths.

The modular furniture system is also becoming an important feature of today’s office. Desks, tables, workstations, reference units and storage facilities can be assembled in “runs” to fit any size or shape of office, making the most economical use of the space available. New items can be clipped into position as required – a particular advantage as, with the slow emergence from the recession, employers can begin to take on more staff and pressure on space becomes an issue once more.

In the end, the purpose of the EC regulations is not to make major, inconvenient changes, but simply to safeguard the conditions in which we live and work. We may complain about the new laws, but it is a fact that the better the equipment we use, the better our productivity and profitability. The furniture industry is now meeting the EC regulations by concentrating on providing a very good version of an very well established item: the desk.

There is enhanced support for Microsoft Office applications and Internet Explorer web pages in Version 3.0 of Spatial Technology’s ACIS 3D Viewer.

The ACIS solid modeller is used in industry-leading 3D software products such as AutoCAD and Mechanical Desktop (Autodesk), Bravo (Applicon), CADKEY (Baystate Technologies), CorelCAD (IMSI), TriSpectives (3D/EYE), TurboCAD (IMSI), ElectricImage 3D Modeler (Electric Image), and over a hundred others which support the industry-standard ACIS SAT file format, which is openly published and freely distributed. Now, this new development enables end users to seamlessly share a SAT file of a complete 3D model between any of these applications.

This means that sales, marketing, finance, technical writing, or other professionals can share their company’s 3D designs with customers, prospects or outside suppliers by embedding the objects in proposals, multi-media presentations, reports or web pages.

Applications for the viewer are seen in engineering design collaboration, supplier/vendor relations, sales/marketing presentations and proposals, technical documentation, customer support, document processing, or product reviews: wherever dynamic 3D models provide added value or visual impact.

ACIS 3D Viewer is ideal for both technical and business users who need to share 3D designs throughout the enterprise through Intranets or with suppliers through “Extranets”. It is most widely used in engineering and manufacturing companies, where ACIS-enabled products are most common and the bulk of the industry’s 3D model content currently exists. The Viewer works with models in the ACIS SAT file format, which is used in over 100 commercially available 3D applications by more than 750,000 users worldwide.

The software provides a direct link between 3D software and OLE-enabled software, as well as a 3D clipboard for cutting and pasting complete 3D models between applications, read/write capability for models created with different versions of ACIS and improved desktop manipulation and visualisation.

The ACIS 3D Viewer 3.0 reads and writes models created in all versions of ACIS, including the new ACIS 3.0, used in Mechanical Desktop (Autodesk) and CADKEY (Baystate Technologies), among others. The new “Save As” command allows file conversion to any ACIS version (from versions 1.6, 1.7, 2.0, 2.1 to 3.0) enabling users to exchange 3D model files with over 100 other ACIS enabled applications.

Multiple models can now be displayed within multiple viewer windows, or the same model can be viewed in multiple windows from different perspectives. Each window can have different camera settings. Standard viewing positions are left, right, top, and isometric, with support for parallel and perspective projections. Users can set their own views by manipulating the model with dynamic zoom, pan and orbit (rotate around the model) functions. The speed and direction of model spin is controlled by the mouse.

Visualisation enhancements include the ability to set the background colour and control entity colours (using the Windows palette), a choice of viewing models in wireframe or shaded (rendered solid) display mode and the ability to set ‘eye’ and ‘distance’ lights. Both lighting and entity colour information are saved with the 3D model in the SAT file.

As an Active Document Server, the ACIS 3D Viewer 3.0 can be used as a standalone application or directly embedded in any OLE-enabled application, like Microsoft Word and PowerPoint, or in Intranet/Extranet web pages. The 3D Viewer works with Netscape Navigator, provided there is an active document server plug-in. Printing and print preview functions are now provided, with user-customisable scaling and printing/screen resolution controls, along with an undo feature which allows users to reverse previous actions.

The Viewer supports OpenGL, runs under Microsoft Windows 95 or NT 4.0 and requires a Pentium computer with 24MB RAM. The ACIS 3D Viewer is available now, free of charge, from Spatial Technology’s web site: www.spatial.com.

“ACIS 3D Viewer plays a key role in integrating the entire organization into the workflow process that drives design or manufacturing”, says Richard Sowar, founder and CEO of Spatial Technology. “Additionally, the Viewer opens new business opportunities for firms in the areas of pre-selling new product concepts to customers, improving customer support, and enabling worldwide engineering collaboration”.

Spatial introduced ACIS in 1989 as the world’s first commercial, object-oriented, 3D modelling toolkit. The company licenses its 3D modelling software development tools to application developers in technical, business and consumer markets.

• David Prawel
• Spatial Technology
• Tel: +1 303 449 0649

February 1998

From an expensive prototype used in the Space Shuttle Columbia comes the affordable peripheral which is taking 3 CAD design by storm – presenting the Space Mouse.

Despite breathtaking advances in digital technology traditional man-machine interfaces such as the keyboard are not well suited for people to use in a 3D graphics environment.

But the Space Mouse is a professional 3D controller specifically designed for manipulating objects in a 3D CAD environment. It permits the simultaneous control of all six degrees of freedom – translation rotation or a combination. The device serves as an intuitive man-machine interface normally to be used by the left hand and supporting its functions as a viewing or guidance hand while the right hand is released to concentrate only on the common construction functions with the help of the pointer mouse or tablet.

The result of years of development for man-machine communication in aerospace and robotic applications the predecessor of the European Space Mouse (known in the US and Asia as Magellan) was the DLR control ball used to control the first robot in space remotely. It flew in NASA’s Space Shuttle Columbia in 1993.

In fact Magellan has its origins in the late seventies when the DLR (German Aerospace Research Establishment) started research in its robotics and system dynamics division on devices with six degrees of freedom (6 dof) for controlling robot grippers in Cartesian space. After lengthy experiments it turned out around 1981 that integrating a six-axis force-torque sensor (three force three torque components) into a plastic hollow ball was the optimal solution. Such a ball registered the linear and rotational displacements as generated by the forces and torques of a human hand which were then transformed computationally into translational and rotational motions and speeds.

The first force-torque sensor used was based on strain gauge technology. Wide commercial distribution was prevented by the high price of about $8000 per unit. It took until 1985 for the DLR’s developer group to design a much cheaper optical measuring system based on six one-dimensional position detectors. The whole electronics including computational processing on a one-chip processor was already integrable into the ball by means of two small double-sided surface mount device boards. The manufacturing costs were reduced to below $1000 but the sales price still hovered in the area of $3000. Only a few hundred were sold.

The original hopes of the developer group that license companies might be able to develop devices towards much lower manufacturing costs did not materialise. On the other hand with the passing of time other ball systems appeared on the market which differed in the type of measuring system.

DLR’s development group spun off a company called Space Control whose objectives were to redesign the control ball idea while retaining the opto-electronic measuring principle reducing manufacturing costs to a fraction of the previous amount so that it could approach the pricing level of high end PC devices. The new manipulation device should be able to function as a conventional mouse and appear like one yet maintain its versatility in a real workstation environment.

Ergonomically the mouse has a very flat and compact design allowing the palm of the hand to rest naturally on the device without fatigue leaving all the fingers free to interact with the mouse cap. This maximises the precision of movements in order to translate and rotate any object in the 3D CAD system screen.

Very slight pressure to push pull or twist the cap in any one or more of the six degrees of freedom is enough to move the object in the screen. Pulling the cap in the Z-direction corresponds to the zooming function pushing it distances the object relative to the viewer. Moving the cap in the X or Y directions drags the object horiizontally and vertically on the screen. Twisting the cap over one of the main axes or any combination of them rotates the object over the corresponding axis on the screen.

Within seconds of using the device the interaction with the cap becomes intuitive. This means that the user handles the object on the scren as if he were holding it in his own left hand observing or guiding it with high precision and helping the right hand to undertake the correct constructive actions on specific points lines or surfaces simply by unconsciously bringing to the front the appropriate perspective view of any necessary detail of the object. And with the integration of nine additional key buttins any macro function can be mapped onto one of the keys thus allowing the user most frequently used functions to be called by a slight finger touch from the left hand.

Now the European Space Mouse is becoming something of a standard input device for interactive motion control of 3D graphic objects in the Catia working environment and for many other applications. There are over 12 0 installations in Europe and US licensee Logitech aims to make it the world standard for 3 graphics interfaces. Silicon Graphics has integrated the interface driver into its new operating system and other leading CAD systems such as Pro/Engineer Ideas Solidworks and Cadds5 have dedicated Magellan drivers.

• Space Control
• Miguel G Leitmann
• 00 49 8105 3769 04

September 1998

Alan Griffiths of IIC Computing introduces a new independent guide to investing in CAD/CAM, which is accompanied by a financial analysis tool.

For nearly 20 years, CAD/CAM systems have been changing the ways companies approach design and manufacture. Despite the obvious benefits, managers still find it difficult to put together straightforward financial justifications for the investment required. Recognising this problem, 13 leading companies, all members of the CAD/CAM Forum of the Computing Suppliers Federation, have sponsored an independent guide to investing in CAD/CAM and an accompanying financial analysis tool.

Chapter 3 of the guide deals with measuring design productivity. Simple measurement of design activity, says the guide, will lead to a justification based on design productivity. There are two key areas to think about:

• Limiting the fall in productivity during the early weeks or months of use; and
• Optimising the productivity gain thereafter.

It is possible to limit the fall in productivity by training users in advance of or during system installation and by using on-site trainers who can transfer expertise to existing staff. Careful selection of the work to be done on the new CAD system and investment in appropriate hardware and software will also help satisfy the users’ performance expectations. It is found that users who work in 3D are on average 20% more productive than those who can work only in 2D.

To look beyond design productivity as the basis for justification it is necessary to have a vision of how CAD technology has got the potential to change the fundamental way a company conducts its business. It is a difficult task, but it is the start of making the company “world class” in its approach to design, manufacturing and support management.

Time-to-market is vital to competitiveness and, with today’s increased demand for product variation, there is a consequent reduction in the life cycle of products. A manufacturer can afford to go over budget in order to bring a product to market more quickly, more than it can risk the product being late to market. The effect is more than just “having a product to sell”, or “completing a project”. Those who move fastest realise higher profit margins and may even be the only ones who survive.

CAD can improve responsiveness to market changes by simulating the product electronically. This allows savings to be made in every step of the business process, from proposal preparation to design review and acceptance, through to manufacture and build.

Quality is usually treated as a cost. Improving quality is usually justified on the basis of reducing scrap and rework. But product quality is not a cost, it is a potential asset. Quality can be “built-in” at the design stage, hence it is essential to have a CAD system where more design alternatives can be tested and where significant analyses can be performed to assess the design and the quality of the design, at the design stage.

It is important to improve the potential CAD users’ perception of quality as a design criterion. Improved quality reduces costs in other areas:

• less inspection and quality assurance
• reduced warranty payments and service costs
• a reduction in the need for contingency or safety stocks.

Manufacturability and the effective use of resources are a key second focus in CAD justification. Items that are easy to manufacture are hence cheaper to manufacture.

Other spin-offs of CAD include faster, more accurate and better presented proposals. There is a better chance of the customer getting what was asked for and CAD can eliminate unprofitable orders caused by inaccurate quotations. CAD helps with component standardisation, allows greater flexibility in the manufacturing process and reduces inventory and work in progress. All these benefits can (and should) be quantified.

As the number of regulations grows, it becomes increasingly difficult to conform and, equally importantly, to demonstrate conformance. CAD/CAM systems provide a means of recording the design process electronically, as the files are computer-based. Also, standard design elements and components can be stored on the system and re-used, meaning that they only have to be checked once and also that everyone will be using the compliant version. This is a good start towards ISO 9001. Many CAD companies also offer Engineering Data/Document Management Systems (EDMS) or Product Data Management (PDM) capability, which is useful when other documents and related data items also need to be managed. It is important, however, to remember that EDMS and PDM capabilities are not normally included in a CAD/CAM system and they should be evaluated separately.

Many companies have already installed or planned other systems such as analysis (finite element, kinematic, electronic), production (enterprise resource planning, computer aided process planning, numerically controlled machining) or data management (engineering document management, product data management, maintenance management). The strategic plan should take into account how these will be integrated with the chosen design systems.

Nowadays, it is a very straightforward task to transfer files from analysis to design to manufacturing systems and to achieve dramatic time reductions. If required, closer integration between systems can also be achieved, but careful planning and selection are needed.

• The IT Centre
• Tel: 01905 613236
• Contact: Roger Crumpton

November 1997

Alan Griffiths is a design consultant to the plastics industry. He offers his personal and thought-provoking views on rapid prototyping.

At the moment it does not seem to matter which engineering journal one reads, the headline “Rapid Prototyping” so often stands out. The expression seems to have crept insidiously into the designer’s vocabulary.

The problem is the constant use of the word “rapid”. Maybe next year, the buzz word will be “rapid, rapid prototyping” and then again at the turn of the century will it be “rapid, rapid, rapid prototyping”?

Prototyping – modelmaking – has always been a part of development engineers’ armoury and they have always had to choose between one of many prototyping routes. In the 1950s and 1960s, prototyping was often achieved by taking an existing product and cannibalising it, in order to produce the Mk II or Mk III versions of the original product. The approach often resulted in aesthetically sub-standard products, but on the other hand, it frequently ensured that the best elements of a product design were carried forward.

Undoubtedly, the expression “rapid prototyping” is now frequently used, due to the wider use of 2D and 3D computer aided design. The use of CAD-generated information has now made it possible to generate prototypes without using the traditional modelmaking process.

But examining the various stages of product development shows that the time allocated to build prototypes occupies a relatively short period of the total development programme. Todays marketeers, sales managers and managing directors, now aware of the expression “rapid prototyping”, are more likely to procrastinate just a little longer before making decisions, hoping to catch up by “rapid prototyping”! But if they understood that a “normal” prototype took four weeks to produce, as opposed to a CAD-assisted model taking two weeks, they would be obliged to make their decision to “press the button” just two weeks earlier in order to meet the same eventual target dates.

Please don’t think that I do not fully appreciate the advantages of the latest CAD-aided prototyping manufacturing methods. In fact, it is likely that before the end of this century we will see more user-friendly CAD stations operated by proficient young designers and that, as they draw on their screens, a model will be produced simultaneously. Unless virtual reality takes over thus bypasses the prototyping stages completely!

However, there are alternative ways of hurrying along projects before prototypes are produced. One way is to convert computer-generated designs into photo-realistic renderings, such as the illustrations shown here produced by Adrian Dodds Design Service. This is a relatively convenient method of producing three-dimensional coloured illustrations and presenting them in such a way that the ideas can be easily understod by sales and marketing people, who might otherwise have difficulty intepreting engineering drawings.

Such renderings can be rotated easily to illustrate alternative views and perspectives, while colours, shadings and backgrounds can be changed at the press of a button. The ability to carry out these adjustments with precision and speed gives photo-realistic renderings the edge over conventional freehand illustrations. A further advantage of this approach is that digital data can be utilised to produce video presentations which illustrate the product in service, prior to commissioning prototypes. Adrian Dodds supplies fully-edited videos of broadcast quality; they demonstrate the features and benefits of the product and and include title sequences and a professional voice-over.

In practice, this “digital-imagining” approach is of most benefit when the eventual end product is large, when the cost of abortive modelmaking could be prohibitive.

While the most high-tech methods of prototyping will continue to gain support and momentum, traditional modelmaking mathods should also be considered before computer-led solutions are used. There is till much to said for using highly skilled modelmakers to produce prototypes. One advantage of this approach is that the skilled modelmaker adds a human input to the product design. I know of one traditional modelmaking company which specialises in taking “failed” CAD information and swiftly building vacuum forming tools which can then produce prototype plastics automobile trim panels for the stylist’s approval. There will always be a need for competent designers to be trained to produce pencil and paper sketches for some of the more intricate design details before turning to their CAD station.

One of the lecturers at a recent seminar at the Victoria & Albert Museum was the highly respected industrial designer Paul Priestman, who has clients in the USA ad mouldmakers in the Far East. As expected, Paul appeared to be preoccupied by cost and speed and spoke of frequently burning the midnight oil in order to satisfy his clients’ needs. Understandably, his office now has no drawing boards and relies heavily on CAD stations, as well as rapid prototyping. He said that on some occasions, they send their latest “drawings” by modem to their clients in the USA and they, in turn, would modem the “drawings” to the toolmakers in Korea.

Thus the mouldmaking would be taking place to the designer’s notes before Paul returned to his the following day! The frightening thought is that eventually one may be able to call in electronically-friendly, globally-located partners, so that a product can be manufactured between the time the designer has supper and finishes breakfast. That would indeed be rapid!

• Alan Griffiths

Every time you see a technical document where parts of a formula have been added in by hand because the word processor used can’t handle mathematical symbols, you’re reminded that the folks behind PC-based maths software have still got plenty of potential users to go for.

There are several applications on the market which will turn your PC into a tool which can solve those equations and print them out too – and do a lot more besides. Two came our way towards the end of last year, but as we know exactly what this sort of software can do, we thought it would be more interesting to give them to a reader who hadn’t been exposed to the suppliers’ marketing machines. Arthur Redsell takes a look at the latest versions of two of the longest established PC-based maths toolkits on the market…

From logs to models

Over the last forty years we have replaced our log tables and slide rules by electronic calculators, extended the scope of the calculators to include all sorts of in-built trigonometric and statistical functions and then widened the applications to handle whole fields of data in the form of numerical ‘spreadsheets’ on our computers. Within the spreadsheets, the many available ‘functions’ help us perform repetitive mathematical operations quickly of whole fields of data – and if need be, to plot out the results.

Essentially, spreadsheets are intended to deal with multiple manipulations of relatively simple complexity, although the degree of manipulation which the formulas can achieve will also depend on the mathematical knowledge and skill of the operator as well as the range of in-built functions available.

Now, over in industrial design, once the intuitive and artistic ideas have been formed, there is a need to prove the integrity and reliability of the concept through the application of mathematical analysis. Here ever more complex formulas and functions come into the design calculations along with the necessity to solve the equations which themselves model the functioning of any proposed system. While the ‘flair’ may be fun, the proof is often hard-bitten graft, and not what our spreadsheets offer us. Enter the two maths programs which we have been looking at this month: TK Solver Release 3 and Mathcad 8.

Both of these are complex, expensive, specialist programs which are unlikely to interest the happy dabbler. Just as the fanciest, spell-checking, grammar-correcting, word processor is never going to turn its user into a Shakespeare or a Wordsworth, so similarly neither TK Solver 3 nor Mathcad 8 is going to turn a novice into a mathematician. Users will need to have a very good grounding in maths to be able to use these programs successfully. But in competent hands the software will be of enormous benefit to designers in handling the calculations which they must do to satisfy themselves that their ideas are practical and reliable.

TK stands for ‘Tool Kit’ and the TK Library provides an extensive selection of files under the categories of Utilities, Mathematics, Statistics and Applications along with numerous examples of their use. These built-in demonstrations can, at further cost, be supplemented by whole libraries of examples taken from such standard works as Roark and Young’s treatise on stress calculations, and from standard ‘works’ on thermodynamics, finance, machine design, queuing theory and etc.

Mathcad 8 goes to similar lengths to provide the beginner with adequate guidance on how to set up a problem for solution. It is this procedural technique which the novice is going to have to master and it is where the user’s learning curve will be the steepest. The manner of doing this differs between the two programmes.

TK requires the problem which requires a solution to be set out on a ‘Rule Sheet’ with a build-up somewhat akin to creating a Spreadsheet. The rules define the relationships between the variables and other quantities, with the variables then automatically appearing on another ‘Variable Sheet’ on which Input or Output Values can be set. Other sheets define lists of values, functions, unit conversions etc. In the ‘Mathlook’ sheet a snapshot of the equations is built up.

The Mathcad 8 approach is different, but equally widespread in application, and appealed somewhat more to me personally because here the problem was defined exactly as it would have been if worked by hand on the blackboard or workbook, the resulting layout looking just like a text book example.

In addition to the numerous example workings, both programs are backed up by extensive files of functions and tables of properties. The functions available cover Integral and Differential Calculus, Boolean Logic, Matrices and Iterative calculations with the ability to produce 2D and 3D plots of the data.

Wizards are on hand to help with setting up and all the usual facilities to drag and drop, link and embed to produce first rate reports including as much or as little detail (or hidden propriety data) as is required or is commercially desired.

World Wide Web interchange of ideas and new solutions, plus the usual technical back-up facilities, make these powerful programs a very worthwhile investment for those people involved in the design of products and systems where mathematical analysis is at the heart of their job. Come to think of it, where is it not? AR

• Mathcad 8
• Adept Scientific plc
• 01462 480055
• http://www.adeptscience.co.uk

• TK Solver 3
• Universal Technical Systems
• +1 815 963 2220
• http://www.uts.com

January 1999

Are you faced with the problem of implementing CADCAM technology for the first time? Or upgrading to a new generation of system? One of the headaches is interfacing with other systems.

The single most difficult area in defining system requirements is interfacing data both within the organisation and with external partners or design teams. It needs to be addressed first at a strategic level as regards possible choice of an industry or project standard (see panel). At a technical level you need to ensure maximum compatibility of transfer. The responsibilities for converting and adapting data input and output need to be well defined within the system supply contract.

Setting a strategic standard for design model storage and exchange such as IGES or STEP might be a requisite for major collaborative projects. This could involve an additional overhead of knowledge and understanding and may add cost or restrict choice. A pragmatic decision based on the most interchangeable format within and between your supplier and customer community could point to the use of IGES DXF or even a vendor-specific CAD file format. However in this case you should be aware of possible inconsistencies in file conversion to and from intermediate formats. Version-specific variations of native CAD formats can also cause problems.

If you have specific in-house interface requirements between for example CAD CAM and MRP systems then you should stipulate the level of interfaces that you expect as part of the RFQ (Request for Quotation) document. Most vendors will publish specified input and output formats but these may need adaptation for successful interworking between systems. Usually it is sufficient to modify only one of then systems to ensure a match but be sure to stipulate who is responsible for doing so. “The output from System A will be adapted by Vendor A to meet the published input specification of System B.”

Assuming you are not a first-time CAD user your legacy data will be in two forms: electronic and paper. Re-use of drawings from a previous CAD system will depend on possible exchange formats and also on a strategy choice as to the revision and conversion philosophy. This may be dictated by the “switch-off plan” for the legacy plan. Bear in mind the cost of ongoing software support ageing hardware and the availability of trained staff. The “convert or redraw” decision for the component drawing libraries will affect the time taken to get up to speed with the new system. Take advice from your system supplier as to the likely limitations of re-using existing elements in a 3D system and the possible short-cuts from bought-in libraries.

Paper drawings will find their way into every design organisation. Scanned paper drawings can form a vapid part of an electronically issued and managed design documentation set in their own right. Suitable viewing and red-lining tools can provide a useful communication channel for approvals distribution and archiving.

Revision or change management will be part of the NPI process as previously defined and many of the basic productivity benefits from a CAD implementation arise from the ease with which drawings can be revised. These benefits will only begin to accrue or course when a significant number of CAD-generated drawings complete the cycle and are due for revision. Consider therefore scanning and converting existing project drawings prior to revision. The CAD tools can then be used to update them.

Full design change automation requires significant process analysis and implementation usually involving an EDM or PDM system to move the change requests and associated drawings through the organisation. If you are not ready to make this sort of commitment it is advisable to start by using your existing paper-based procedures for the change notes and descriptions and to make the final changes to design files using CAD. Electronic red-lining can then be used selectively – for example to transmit change requests from the shop floor – the electronic red-lines being treated as electronic paper forms.

A free executive guide is available from the Computing Suppliers Federation (CSF) offering advice and guidance for managing system implementation effectively. Intended for directors and managers of engineering and manufacturing businesses in the widest sense it covers advice from the early stages of setting the business objectives through supplier selection to achieving the expected benefits once the system is commissioned.

STEP

For the extended enterprise and for larger companies using many different applications (eg two or more CAD systems) file exchange standards such as DXF and IGES do not provide a satisfactory solution. Data translation results in three versions of the same data – a version for each of the target and source applications and a version for the neutral format. Such a circumstance can quickly result in problems of version management and access control.

STEP is defined in an international standard – ISO 10303 Its primary function is to provide a system-neutral product model. This satisfied the need to share data between applications within an organisation and externally with team members in other organisations. STEP is independent of any system and enables the description of product data throughout its life cycle. Its nature makes it suitable not only for file exchange but also as a basis for implementing and sharing product databases and archiving.

It is important to emphasise that STEP is much more than a data exchange standard. The existence of a neutral data model which permits data to be stored on any database platform and accessed from any application via a standard API (application program interface) is a powerful concept.

• Computing Suppliers Federation
• Roger Crumpton
• 01905 727610

November 1998

Only in the past few years have solid modelling systems been used in earnest. Has the conversatism of engineers now been truly overcome?

The very first CADCAM systems started by mimicking conventional engineering design – 2D draughting. Lines, arcs and other geometrical entities were mathematically defined in a 2D coordinate system, which could be manipulated and edited easily.

The addition of a third coordinate within the definition was a simple step forward. However, these initial 3D systems continued to use draughting geometry – lines, arcs and splines – producing drawings akin to a physical model made from pieces of wire.

While a wire frame model enabled engineers to picture and resolve 3D issues, such as complex assembly questions, there were also inherent problems.

A 3D wire frame model required more information to be generated and manipulated than a 2D drawing. Models and their subsequent derived drawings therefore took longer to create than a 2D drawing. Equally, a wire frame model is not a full definition of a real world object, which limits its use. Calculating mass properties or an intersection curve, or defining a styled surface was not easy. Such constraints led to surface modelling, where the mathematics of a surface or skin could be defined and manipulated.

Surface modelling enabled complex shapes, such as a car body panel, to be defined in a way impossible before. Such models cold subsequently be used for shaded image generation or machine tool path generation. However, adding surfaces to a wire frame model added yet more data, often making it more cumbersome for general engineering applications.

Solid modelling overcame these problems by combining all the geometry into a single model that fully defined a real world 3D object. A solid model is created by taking standard primitive shapes – cone, cylinder, torus, sphere and so on – together with swept 2D geometry, and joining, subtracting or intersecting the resultant objects together. A cylinder subtracted from a cube produces a hole, for instance.

Like most advances, though, the development of practical solid modelling software has not been straightforward. The mathematics involved is extremely complicated and it has taken many years to arrive at software that enables real world designs to be created.

Initially, some developers simplified the mathematics by faceting a model – breaking everything into lines, While this showed the benefits of solid modelling, the loss of accuracy was often not acceptable to users. Equally, solid models produce large amounts of data and it is only the recent advance in workstation power and PC technology that has provided hardware capable of supporting it cost-effectively.

All design work is more or less iterative, so models need to be easily changed. Initial solid modellers required the lengthy process of re-running the complete modelling sequence to undertake a change. Thus it was that the parametric, feature-based solid modeller was developed.

Here the rules that define the model are captured, so that a change is undertaken simply by changing a dimension or parameter and regenerating the model from the rules. Features are regularly used geometries, such as a keyway or countersunk hole. These are defined as parametric solids which can be added to the model in a single command.

Developments are continuing in solid model manipulation and the best modellers enable the geometric rules to be changed easily, providing a flexibility in design modelling that is a considerable step forward from the earliest CADCAM systems and the manual processes upon which these were based.

Nearly all products are made from an assembly of components. Building an assembly model by bringing individual models into a single part, as provided by early modelling systems, has proved impractical, given the large amounts of data involved and the work required to reflect a component change.

Leading solid modelling systems now dynamically access parts in an assembly, presenting the structure as a graphical tree. This enables the complete product structure to be defined clearly, variants and all, as well as allowing easy manipulation of the assembly.

In the best systems, groups of users can work concurrently on a single assembly, seeing the results of each other’s work as it happens. Thus models with tens of thousands of components – such as jet engines with all their bolts, washers and pipes – can be created and manipulated with ease.

Early adopters of solid modelling often came up against the limitations of the early modelling systems and would advise prospective users to proceed with caution. Quite simply, a solid modelling system is of little use if it cannot model the products you make, at component and assembly level. There are still software packages available today of which this is true.

On the other hand, the best modelling systems bring real benefits worthy of exploration. A solid model provides a far more complete description of the design intent and can be just as quick to create (including the associated documentation) as a 2D drawing. While it does not necessarily remove the need for a drawing, it can be used far more effectively in all the activities that use design data.

Rapid prototyping can reduce build and test times dramatically. Computer-based analysis of models enables fast design optimisation. Tooling and manufacturing design becomes easier and NC toolpaths can be applied directly to the model. With fully integrated systems, changes can be undertaken easily and rapidly and reflected automatically through all the downstream applications.

All this leads to a more engineering process, enabling higher quality, lower cost products to be produced in competitive time scales, as well as allowing time for new technologies to be introduced or new legislative requirements to be met. It is for these reasons that this technique will soon be the natural starting point for most engineering design.

• Desktop Engineering
• Tel: 01993 883555
• Fax: 01993 883201

David J Wilson, principal of Open Archive Systems (OASys) argues the benefits of integrating paper-based and CAD-generated engineering data.

It is estimated that there are more than eight billion drawings worldwide, of which fewer than 15% are in a CAD format. The need to capture, modify and distribute existing paper designs predates CAD technology itself. But with the emergence of standards for storing drawings in raster format, and the emergence of cost- effective scanning hardware and services, the raster environment only came of age in the early 1990s. Today, there is a number of available options to input paper archives or “BC (“before-CAD”) designs into a CAD system.

Manual redrawing: just place your drawings on the desk by your CAD system and redraw them from scratch. A complete redraw of the original drawing is, and always will be, the most accurate method of conversion. It requires little capital outlay and can be useful to convert small numbers of simple designs. However, it is extremely time-consuming and a poor use of the CAD system, as the investment in CAD is being used to create designs which already exist!

Digitising: digitiser tablets are a common CAD peripheral and the technique involves placing a drawing on the tablet and using the puck to trace over the original design, using a CAD system. This method is faster than just redrawing the design, but it is prone to errors and is still labour-intensive and slow.

Service bureaux: outsourcing to service bureaux is a common method for handling small jobs, pilot projects or quick turnarounds. There is a savings on resources and little or no capital outlay for equipment. Bureaux typically use one or all of the methods listed here. These services, however, may not meet the security or design needs of a company. Be sure to choose a partner based on their experience and knowledge of your design practices and needs. Remember, the cost of conversion is directly related to the quality of the end result.

Scanning: scanning paper drawings to work within the proven environment of CAD and the merging environment of EDM or workflow offers the most control in the transition from paper. The scanning process can be customised to fit the individual drawing or its application. Scanning has been successfully implemented in both large and small companies to solve integration problems between paper and CAD.

Once drawings have been scanned, their value increases, because of the ways to use the newly scanned design in a CAD system.

Of companies’ operating expenditure, it is estimated that 7-10% is spent on manual document management processes, re-engineering the flow of information or paper trail. An organisation will realise tremendous savings by re-engineering the paper trail.

Through the implementation of a managed engineering archive, searching time as well as re-engineering time become past history. Substantial savings can also be realised in a managed revision process. The reliance on manual drafting and control of drawing revisions on older documentation can be put to rest.

CAD has already proven itself as a tool to design and maintain product and service documentation. Applying this tool to archived resources allows the CAD advantage to be applied completely. These electronic drawings can then be quickly revised, modified, plotted or copied in a fraction of the time it takes to modify paper designs. The design process can be come highly streamlined, providing substantial cost savings, improved product quality and faster time to market.

Once files are in electronic format, document management can be used to further enhance productivity. Options range from a simple file storage system with limited revision tracking to a system that securely controls viewing, editing and distribution of all engineering-related information.

Many organisations are required to comply with standards and regulations that virtually necessitate electronic document management. According to the British Standards Institute, 47% of ISO certification failure is due to poor documentation control. Cost and time justification can be realised by improving the ECN/ECO process and achieving ISO 9000 certification.

A comprehensive, 12-page guide covering the real-world issues associated with integrating paper-based and CAD-generated engineering data is now available free from GTX Europe, which supplies raster editing and conversion software.

The hidden costs of paper

Manual methods of handling, storing and maintaining paper drawings are difficult, time consuming and costly, since most information is still in paper form. The following are some of the obvious problems:

• Paper drawings, Mylar, bluelines and other media are susceptible to ageing.

• Manual-based revisions are costly.

• Paper is slow to distribute – it takes longer to copy and distribute a single piece of paper than it takes to distribute or reproduce several documents electronically.

• You may be fully modernised with a full suite of CAD software, but what about your contractors, subcontractors and business partners? Many transactions between companies are inefficiently conducted with manual archives, even when the originals may have been CAD files.

• Paper is cumbersome. It is often hard to find specific information in specific documents. Electronic searching is more efficient and faster.

• Paper is restrictive in format. It is limited to graphics and text, while electronic documents can contain hyperlinks, audio and video.

• Paper is static. It can be out of date even before it is distributed because of lengthy release cycles. The added concern of who has the most recent revision intensifies this problem.

• Facility costs for the storage and maintenance of paper archives can be substantial. Justifying a document management system should be based on significant reductions in facility costs alone.

• Paper gets lost. It is estimated that 5-7% of technical assets are lost or mis-filed using manual procedures for handing paper drawings.

GTX Europe

Tel: 01256 843555

Fax: 01256 24634

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