- high load bearing capacity
- known for excellent durability and toughness
- resistant to solvents, oils, ozone, water, mildew, molds and fungus
- good electrical characteristics and properties
Acetal / Delrin
- high mechanical strength and rigidity
- excellent wear
- low moisture absorption
- excellent dimensional stability
- low coefficients of friction
- outstanding wear and abrasion resistance
- high service temperature
- excellent impact resistance
- excellent chemical resistance
Lexan / Polycarbonate
- superior impact and toughness
- high mechanical strength and rigidity
- good thermal properties
- good machinability
Polyolefins Chemical Names:
Low Density Polyethylene (LDPE) ‐ Good tensile strength, excellent resistance to alcohols, bases and acids
High Density Polyethylene (HDPE) ‐ Corrosion and chemical resistant, high tensile strength, lightweight
Polypropylene (PP) ‐ Highly resistant to acids, bases and chemicals, can be produced opaque, translucent, or colored
Ultra High Molecular Weight Polyethylene (UHMW) ‐ very low coefficient of friction, outstanding impact strength
In addition to the basic properties of plastics, additives can be used for products requiring enhanced performance, processing and/or end use optimization. These additives are designed to meet and serve various industries such as consumer goods, medical, industrial just to name a few.
- Antioxidants ‐ minimize or eliminate oxidative polymer degradation.
- Antistatic Agents ‐ minimize the electrostatic charge that may build up in a product due to handling and/or processing.
- Chemical Foaming ‐ Density reduction
- Custom Combinations
- Flame retardants
- Mineral filler ‐ Performance enhancement or cost reduction
- Process Aids ‐ Surface modification and performance enhancement
- Purge Compounds ‐ Equipment cleaning
- Release Agents ‐ Cycle‐time reduction
- Slip Agents ‐ modify the surface characteristics of plastic materials by altering the surface adhesion or the coefficient of friction
- Slip and Antiblock Combinations
- UV Stabilizers ‐ preserving the substrate's mechanical and physical properties when exposed to UV rays
With requirements for lowest weight, highest thermal conductivity, and ease of machinability, tool and mold applications are a natural opportunity for aluminum. Aluminum producers have responded with often‐proprietary and tradenamed products tailored to meet the diversity of challenges presented by these applications.
Hopefully, this can explain some of the key elements. But, first the question of “why aluminum” needs to be addressed. Alternative materials, particularly a range of steels such as P‐20, H13 tool steel, and stainless steels as well as copper based alloys often containing beryllium, have been employed in tool and mold applications.
They offer high strength and wear resistance,and, in the case of the copper alloys, thermal conductivity as well. But no material has all of the desired properties for a given application, and the alternative materials are no exception. They are heavy, often less machinable, and in the case ofthe steels, have poor thermal conductivity.
Overcoming those deficiencies is where aluminum comes into the picture. Compared to steel, aluminum:
- Has a four‐fold increase in thermal conductivity. In molding operations, this reduces the required cooling cycles and also minimizes local hot spots that could lead to part distortion. Aluminum also allows for the design of simpler cooling systems, which require less design and machining time.
- Is lightweight. Aluminum has roughly one‐third the density of steel.This makes handling of the tooling and molds easier, and allows faster opening and closing of molds and tools due to reduced inertia. In addition, lighter weight tooling results in less press wear reducing maintenance and downtime. These benefits are particularly relevant to large tools and molds.
- Can be machined and polished more rapidly. Depending on the specific aluminum alloy, machining rates three to ten times faster than that for steel are possible. This reduces the time required for mold production, particularly for large molds with deep cavities.
- Exhibits high electrical conductivity. This, along with a lower melting point ascompared to steel, enables the use of electrical discharge machining of aluminum at a rate four to five times higher than for steel.
As a result of these benefits, using aluminum for mold applications can save 30% in cost over steel in mold manufacturing, increasing to 40% if the reduced part production cycle times and hence improved productivity are included.