Ten golden rules to make tool steel buying fun
This article was originally written in the period 1995-2000
Follow these 10 golden rules and you can be sure that your life will be full of interest and excitement. In the longer term, there is also the distinct possibility of an extended period of leisure!
Rule 1. Always buy tool steel at the cheapest possible price per kilogram. Be absolutely certain never to enquire how big the plus tolerance will be. You will then rightly be able to claim that you bought the resulting swarf at the lowest possible price. Never ask for a price per piece!
Rule 2. Where possible, purchase blocks from a supplier who cuts them every which way from much bigger blocks. That way you stand a good chance of sinking the impression into what was the centre line of the original ingot with its potentially doubtful analysis and properties. You can then look forward to many hours of stimulating discussion with your customer whose tooling has only run 25% of its normal life before failing.
Rule 3. Always purchase standard commercial qualities whatever the job in hand. This is particularly important where the job is very complex and requires a highly polished or textured finish. The sheer excitement of finding a tiny defect during final polishing is impossible to describe particularly if you have already spent ten thousand plus. This rule can also provide great fun for gamblers, nine-nine times out of one hundred there will be no problem, will you hit the jackpot with the next one? Look forward to many happy hours pursuing a hopeless claim against your supplier and making a new tool. Never be fool enough to pay more for ESR or similar special qualities that often carry a guarantee against defects.
Rule 4. Never ask a supplier to stock material machined close to your final size and with the correct grain flow. This would spoil all the fun of machining off the surplus tolerance that you have paid for. Furthermore, the correct grain flow will usually enhance tool life so you will not be able to sell so many.
Rule 5. Always assume that all tool steel at whatever price and from whatever source is of the highest possible quality. This will give you a valuable opportunity to brush up on your metallurgical terminology as you read reports on central unsoundness, piping, decarburisation and surface cracks to name but four.
Rule 6. Never bother to calculate the benefits of buying pre-machined bar. Your skilled staff and expensive machinery will thrive on some occasional “roughage”. This is adequately provided by the need to remove the hot rolled black surface and decarb and to square up. The yield loss on machining is not significant ? is it?
Rule 7. Always EDM tool steel in the annealed condition as supplied. That way you will enjoy the challenge of correcting any slight movement in heat treatment by careful grinding. Never enquire about pre-hardened blocks that only require EDM as the final operation.
Rule 8. Ignore new surface treatments such as laser hardening or ion implantation (*). Stories that these technologies can extend tool lives up to eight times are obviously hogwash!
Rule 9. Ensure that your well-deserved reputation among suppliers and customers for knowing all there is to know about tool making is protected at all costs. If you have any doubts, ignore them. Above all, never ask for advice!
Rule 10. Always buy commodity type tool steels from non-specialist suppliers who operate on the “pile it high, sell it cheap” principle. When something difficult comes up, your specialist tool steel supplier will always be around to help, or course.
(*) Ion implantation is a unique process, developed by AEA Technology at Harwell, in which an accelerated beam of ions is fired into the surface of a tool. These ions (“charged particles”) penetrate into the surface layers, selectively changing the chemical and physical properties of the materials surface layer without affecting desirable bulk substrate properties.
Ion implantation can improve wear resistance, hardness, fatigue failure resistance, corrosion characteristics, coating adhesion and reduce friction. The surface properties of almost any metal, ceramic or polymer can benefit from ion implantation.
The technology has been extensively developed and tested and is reliable and reproducible, making it ideal for high-performance, high-precision components. Injection moulding nozzles have typically been found to benefit from a four fold improvement in life, with increased throughput. Tool steel and chromium plated moulds, slides, tapers and gates can often have lives extended by a factor of four with improved release properties.
Ion implantation is a low temperature process which causes no distortion, growth or loss of existing hardness and any element can be implanted to create beneficial surface alloys. Finished tools with polished or textured finishes may be treated as a final operation without risk of damage. Successful applications already include injection moulds, press tools, punches, dies, drill bits, extrusion nozzles, injection moulding screws, tool inserts and many others.
- Carrs Tool Steels