Tool steels have historically been over-used for injection mold cores and cavities, simply because they've been both cheap and familiar. But soaring price tags on many tool steels, coupled with the push for more productive molding operations, is triggering an investigation of alternative mold construction materials. While not necessarily cheaper than steel on a price basis, these alternatives have thermal engineering or maintenance cost advantages that make them more attractive than ever. Copper alloys are one choice. They can speed the removal of heat from critical sections of the tool, potentially improving cycle times 20 to 50 percent and even improving the dimensional stability of the molded parts themselves. Look for more stainless steels, too. Stainless has always been the material of choice when molding acid-emitting resins, such as PVC. But now use of stainless is spreading, particularly for expensive tools, because corrosion-related maintenance efforts and costs are reduced through the life of the tool. Finally, important advances are also under development with aluminum mold materials, particularly in strength, surface hardness, corrosion resistance, and uniformity after heat treating (go to the Design News Materials Forum at http://rbi.ims.ca/4921-511 for more information). Here's a look at three recent mold materials that can serve as steel stand-ins:
Improved Stainless RoyAlloy is a new stainless mold-base steel, developed by Edro Specialty Steels, to overcome shortcomings associated with prehardened 420F (1.2085) stainless holder steels: a lack of toughness, unpredictable stability, inconsistent machinability and poor weldability. Edro says thermal treatments give the material improved dimensional stability after machining without the need for stress relieving. Simplified Plumbing The photo shows a MoldStar 90 beryllium-free copper alloy core for a 32-cavity mold running a polypropylene part used in a packaging application. "Because of the conductivity of the alloy, a water channel is cut only in the base of the core, in place of an intricate, small, water system normally needed had the material been tool steel," comments Cliff Moberg, president of Performance Alloys.
Molding Mounds MoldMAX V is a new copper-nickel-silicon-chrome alloy that has a hardness of 30 HRC and thermal conductivity approximately four to five times greater than P20 tool steel. The new grade is the second in a series of non-beryllium-copper alloys introduced by Brush Wellman. Moldmax XL is a copper-nickel-tin alloy with similar properties.
An envelope is a common packaging item, usually made of thin flat material. It is designed to contain a flat object, such as a letter or card.
Traditional envelopes are made from sheets of paper cut to one of three shapes: a rhombus, a short-arm cross, or a kite. These shapes allow for the creation of the envelope structure by folding the sheet sides around a central rectangular area. In this manner, a rectangle-faced enclosure is formed with an arrangement of four flaps on the reverse side.
Halloween isn’t just a time for creative costumes. Thanks to the element14 online design community, the holiday this year also brings us a number of creative electronic device design ideas aimed at making your Halloween party a unique experience.
On April 15, 2010, President Barack Obama gave a major speech at the Kennedy Space Center in Florida, announcing that the US would send astronauts to Mars by the mid-2030s. But in order to do so, NASA would first need to ramp up its capabilities through missions directed toward "a series of increasingly demanding targets," i.e. asteroids.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.