Injection Mold Steels – What You Should Know

In an age that demands high productivity in manufacturing, there is no substitute for high quality injection mold in your injection molding process. Given the wide variety of injection mold steels available today, proper selection must take into account not only price and traditional practice but why they are used. In order to make the proper selection, one must understand the multiple demands that are placed upon injection mold steels, depending on the specific application. There are two major categories of demands which, together, highlight 12 desirable qualities.

Injection Mold Demands

1. Wear Resistance – Important to consider for cavity components if the plastic material is abrasive, filled with glass or minerals.
2. Toughness (Impact Strength) – Can be an important factor in repair or component replacement cost.
3. Compressive Strength – Needed to withstand injection mold clamping forces to minimize damage to shut off areas.
4. Heat Treated – Needed when injection molds operate at high temperatures.
5. Corrosion Resistance – Very important in two major aspects – first when corrosive plastics or additives are used; and second, when injection mold operate in high-humidity areas or regions where the water is particularly corrosive.
6. Thermal Conductivity – Can have an impact on the cycle time of high-production injection mold and although it’s not often a major factor in selecting mold steels, it is a reason for choosing beryllium copper instead of steel in some cases.

Injection Mold Makers Demands

1. Hobbability – Permits production of numbers of intricate injection mold cavities. With the use of EDM (Electrostatic Discharge Machine), hobbability is becoming less important.
2. Machinability – Of great economic importance for the injection mold maker.
3. Polishability – Cavities that require a mirror-like finish must be made of special injection mold steels.
4. Heat-Treating Dimensional Stability – A steel with good dimensional stability must be selected.
5. Weldability – An injection mold steel should be considered because of part design and engineering changes or repair because of tool damage.
6. Nitriding Ability – Nitriding gives a very hard surface layer to the steel and very good resistance to abrasion or corrosion. However, the nitriding layer (2 to 10 mils thick) is very brittle and easily cracks if subjected to impact blows, rapid temperature changes or uneven pressures.

To learn more about Injection Mold from Total Solution Plastic visit our website, or use our Contact Form to email us.

Franklin Spears
Total Solution Plastic
7613 Pats Branch Drive
Raleigh, NC 27612
919-900-8801