It is not always to easy to know how to choose the right tool steel for injection mold making. Not only that, but choosing the wrong one can spell disaster for all your hard work! More than one core or cavity has cracked or worn out long before its time, due to the wrong choice of tool steel.
A good relationship with your tool steel supplier is an important part of the mold making process. A reliable source of quality steel, delivered on time and to the right specifications helps reduce the chance of error or a late delivery date.
Get the tool steel the size you need and save money with semi-finishing work. They are set up to cut and grind to suit; take advantage of this service.
Tool steel applications and properties
- Will the mold run at a high temperature?
- How important is the surface finish?
- How many pieces do you expect to get from the mold?
- What kind of material will be injected into the mold?
- Is the mold highly detailed?
- How do you plan on machining it?
- How critical are the dimensional tolerances?
- Are there moving parts, such as slides and lifters?
- Will the hardened steel be coated?
- Will the mold be etched or chemically treated?
- What about the thermal conductivity during the molding operation?
- What type of molding will you be doing? This could be thermoplastic, thermosetting, two color molding, overmolding, insert molding, blow molding or compression molding. There are even more types of molding such as extrusion, vacuum molding and RIM molding.
Basically, for injection mold making, you need to decide on through hardened or pre-hardened tool steel.
Some low-production molds are even made of aluminum, such as the high grade QC-7. Then there are tool steel castings, cast epoxy/steel blends, beryllium copper, and other materials.
Through Hardened Tool Steels
Pre-Hardened Tool Steels
A good tool steel supplier is an important part of your overall success
Once you develop a good working relationship with your supplier, respect that because he is very critical to your success. It is not wise to bargain hunt for the cheapest steel around; you will be penny-wise and pound foolish. The steel represents only about 5% of the total cost of a mold anyway!
Your supplier will have the experience and knowledge to guide you and keep you informed when a new steel is developed, or a process comes along that can benefit you. Plus, they have the heat-treating information you need, suggestions on which steel is appropriate, which steels should be used in combination, etc.
Should you do heat-treatment in house?
If you have enough volume or your operation is far away from a heat treater, yes. Otherwise, you can get great service from local heat-treaters who are expert at what they do and will have a very fast turn-around. Your parts will be cleaner, the heat-treatment more reliable and the cost is generally lower than the expense of a furnace and the utilities to keep it up and running.