How far apart are P-20 steel and beryllium copper in numbers?
They are far apart on thermal conductivity and close on hardness and strength. The table below is taken from the "Compare MoldMAX alloys with other materials" table on Materion's MoldMAX page, showing P-20 steel and the two beryllium copper MoldMAX grades on this site.
| Material | Rockwell hardness | Thermal conductivity (BTU/ft·hr·°F) | Yield strength (ksi) | Tensile strength (ksi) |
|---|---|---|---|---|
| P-20 tool steel | 30 | 17 | 120 | 140 |
| MoldMAX HH | 40 | 75 | 145 | 170 |
| PROtherm | 20 | 145 | 90 | 105 |
MoldMAX HH is harder and stronger than P-20 in this table, and Materion states it conducts heat four to six times better than standard tool steels. PROtherm gives up hardness for the highest thermal conductivity in the table.
Why does thermal conductivity affect cycle time?
Because the plastic part has to cool in the mold until it is rigid enough to eject, and cooling is a major part of every shot. A mold material that moves heat from the cavity surface to the cooling channels faster lets the part reach ejection temperature sooner. Materion says MoldMAX gives a shorter cycle time and better part quality, but publishes no percentage, because the real gain depends on the part, the resin and each mold's cooling design.
Materion also says that MoldMAX inserts in steel molds cool hot spots, reduce or remove the need for cooling channels where they are hard to drill, and even out mold temperatures for tighter tolerances and less post-mold shrinkage and warping.
Does the whole mold have to be beryllium copper?
No. The usual approach is to keep the mold base in steel and use beryllium copper only for the parts that are hard to cool: core and cavity inserts, parting-line inserts, sliders and lifters, or hot runner tips, the applications Materion lists. More on this in What is a mold insert?
What should you weigh before choosing beryllium copper over steel?
- Hardness versus conductivity: the most conductive grades are usually softer, so choose by whether the spot needs wear resistance or heat removal more.
- Not every MoldMAX grade is beryllium copper: MoldMAX V is Cu-Ni-Si-Cr and MoldMAX XL is Cu-Ni-Sn.
- Repair: Materion offers WeldPak and WeldPak XL filler metal for TIG repair of the beryllium copper MoldMAX alloys.
- Machining, grinding and welding need dust and fume control per the SDS; see Is beryllium copper safe?
All grades and the full comparison are on the MoldMAX page.
Frequently asked questions
- How much better does beryllium copper conduct heat than P-20?
- It depends on the grade. Materion says MoldMAX HH conducts heat four to six times better than standard tool steels, and its table lists P-20 at 17 BTU/ft·hr·°F against 75 for MoldMAX HH and 145 for PROtherm.
- By what percentage does beryllium copper cut cycle time?
- Materion publishes no percentage; it states only that cycle time is shorter and part quality better. The real result depends on the part, the resin and the cooling design.
- Is beryllium copper hard enough for injection molds?
- Materion says MoldMAX offers the strength and wear resistance of tool steels, and its table lists MoldMAX HH at Rockwell hardness 40 against 30 for P-20 steel (the table does not state the scale).
References
Sources read on 5 October 2026. Producer data changes; confirm values against the current datasheet before design.