Toolform Case study:
Laser and Sheet Processes Group

New Die Steel Materials for Drop Forging Applications

Examples of dies prepared for forging (Photo courtesy of Kespar Engineering Ltd)

The Toolform programme, joint funded by the DTI, Yorkshire Forward and Objective 1, has assisted in the assessment of new die materials wear using heat treated die steel for a West Midlands based drop forging company. Smethwick Drop Forge (SDF), located in the West Midlands, is a leading manufacturer of forged components and parts produced by a hot drop forging process. Its sister company, Kespar Engineering Ltd, is a leading UK tool repair and reclaimation shop, with full machining, heat treating, design and finishing facilities.

Many forging companies have discussed the problem of increasing tool life and reducing wear problems with TWI. The Toolform programme has been an excellent conduit for assessing the performance of new and specialist alloys for the forging industry. Currently the most popular die tool material is H13 tool steel, and this dominates the market on the basis of good performance and relatively low cost. However, specialist materials are being developed for the forging industry. Bohler Special Steels UK, have materials with variations in chemical composition over H13 and use a more rigorous manufacturing route. This involves using predominantly virgin raw materials and then primary melting in air followed by pressurised ESR (electroslag remelting) of the steel. The tool steel produced in this way offers enhanced properties over an H13 material, exhibiting hardness values of around 55HRC after heat treatment. What is not known is whether these improved properties translate into improved performance in service and therefore extend usable tool life. The high purchase price, coupled with little UK experience about how it will perform in specific forging applications, has lead to a reluctance from forging companies to purchase tools made from this material. The material has not, therefore, been tested during actual forging operations in the UK.

Examples of die cavities (Photo courtesy Kespar Ltd)

A project to compare the performance of the new material was developed between Bohler, Kespar, SDF and TWI. The materials used in the forging trials were supplied by Bohler Special Steels. Material blocks were heat treated and machined by Kespar Engineering Ltd, with forging trials performed on the drop forging equipment at SDF Ltd. TWI assisted with metallurgical examinations on the worn dies. When forging automotive components using the new material, over 90% increase in tool life was achieved, demonstrating the effectiveness of the new material.

This support, provided to SDF and Kespar, was made possible through the Toolform Strand of the Advanced Metals Technology Initiative (AMTI) funded by the DTI, Yorkshire Forward and the European Union through the South Yorkshire Objective 1 programme. The AMTI project is managed by NAMTEC, the National Metals Technology Centre. For more information email eliana.fu@twi.co.uk.