Simple Solutions That Work! Issue 11

PAUL BRITTON President INTERNATIONAL MOLD STEEL, INC. ARTICLE TAKEAWAYS: • Understanding die steel grades • H-13 versus DH31-EX I n today’s die cast market you have many different steels to choose from. North American Die Casting Association publishes a list of different types of Hot Works steels to choose from when selecting a material for an upcoming job. The different materials range from Grade “A” to Grade “F.” Each grade has a different chemistry or quality that different tool shops might be looking for with regards to their tooling. Quite a few times companies will choose a simple H-13 single melt or double melt material. These types of materials are usually the least expensive types on the NADCA list. Most tool shops are very familiar with these materials; therefore, the learning curve is basically non-existent. But should they be chosen above others because of those qualities? In some instances yes. But when it comes to die life and tough jobs that need a better steel, then no, it would be best to choose something different. Below are 3 case studies of companies that originally chose a double melt H-13 but then through trials, these companies found something that provided better value and cost savings. CASE STUDY #1 Automotive Valve Cover Challenge: A customer approached us to see if we could help their current die situation. The original material chosen for this job was a typical H-13 double melt material. Their current level of production was set at 900-1400 shots per day off of these dies. The original H-13 (44-46 HRC) dies started to show evidence of heat checking between 5000-8000 shots. At this point the level of heat check is acceptable but does need to be watched. Once the dies hit around 13,000 shots, the dies needed to be welded because the heat check was so bad, making the aluminum parts unacceptable. Then, at around 18,000-20,000 shots the dies needed to be plugged. The cost for this generally runs between $3,500-$4000 for plug rework between the welding and the plugging of the holes in the die. And, the die life is shortened considerably. Once the dies hit 25,000 + shots the dies are nearing the end of their die life. Solution: This customer decided it was time to take a new approach when it came to selecting a die steel for this application. The die steel selected was DH31- EX with a hardness range of 44-46 HRC. DH31-EX falls into the Grade “C” category on the NADCA steel selection chart. This material is known for better heat check resistance as well as high toughness especially in larger cross sections. The trial was set out to be for 3 cavities and cores (Cav #16, #17, CHOOSING THE RIGHT DIE STEEL 66