Proper selection of the appropriate mold material is critical to manufacturing a high-quality mold. Tool steel, aluminum, copper, and alloys are some of the materials used.
How to Eliminate Streaks and Weld Problems with Laser Technology
Laser technology overcomes streaking and welding challenges for new mold textures and texture repair.
Mold Materials: Essential Reading
How to Lower Cycle Times With the Right Tool Steel
Combining excellent mechanical properties, high wear resistance and high thermal conductivity in a specialty tool steel yields cycle time reduction.
Considerations for Mold Base Material Selection
Choosing the right material can greatly affect the profitability and cost of your application.
How to Achieve the Best Mold Finish
A look at factors that impact the polishability of tool steels and recommendations for obtaining a high-gloss finish.
Let’s Be Clear About Aluminum
Within the injection molding industry, a negative perception of aluminum for anything but prototype plastic parts persists, despite aluminum tooling being able to produce and run almost any resin that steel can, as well as produce millions of shots with unfilled resin with uniform results.
Soft Wire Threading for Wire EDM’ing: Tips for Success
Look for EDM equipment that provides improved wire processing during the AWF cycle. Technology should include a way to precisely control the wire tension and energy used to cut the wire.
FAQ: Mold Materials
What are the benefits of alloying tool steel?
Steels with a chromium content of at least 12% are generally considered corrosion-resistant. Martensitic tool steels have a high chromium content of 16% and a carbon content between 0.33%-0.38% that provides quenching and tempering during which only tempering carbides appear in the microstructure, leaving behind enough chromium to ensure corrosion resistance.
The resistance to corrosion is based on the formation of surface layers, protecting the metal from further reaction with oxygen. The most effective element is chromium. In combination with oxygen, it forms an oxide layer (chemical configuration: Cr2O3) on the surface, which shows a dense and amorphous structure as the chromium content increases. The formation of this Cr2O3 surface layer of approximately one nanometer promotes passivation, a process that protects the material against surface corrosion and ensures the functionality of the mold.
Alloying with molybdenum improves resistance to pitting corrosion, as it contributes to stabilizing the passivating Cr2O3 layer. In addition, molybdenum builds into the structure of the layer and strengthens it by preventing the removal of oxygen from the respective layer. Using stainless steels alloyed with molybdenum can also avoid corrosive attacks during mold cleaning, preventing hazardous products from entering the production process.
(Source: The Benefits of Alloying Tool Steel)
How can moldmakers optimize the quality of recycled plastic for molds?
The successful use of recycled materials in injection molding depends on how the original parts are recycled and re-pelletized. The two most important factors for producing a quality pellet of recycled plastic with consistent material properties are:
- Re-melting. Proper re-melting of the recycled material occurs under very low shear rates in the extruder and at the lower end of the melt temperature. The objective is to gently re-melt the original material, which ensures maintenance of the material properties.
- Melt filtration. The proper filtration process will remove any contaminants in the melt like cellulose, metal or wood pieces. State of the art melt filtration is fully automated and does not require manual operation steps. The melt is filtered continuously at low pressure and can remove particles as small as 70 microns in diameter.
Today’s recycling systems can help produce consistent quality plastic pellets that moldmakers can use in a wide variety of injection-molded parts.
(Source: Putting Recycled Plastics to Work)
