The manufacturing process known as molding, or moulding, produces various parts by utilizing pliable material that is formed against a rigid form, known as a mold or matrix. With raw material, such as glass, amorphous metals, plastics, fiberglass resin, or rubber, filling the mold cavity, molds themselves can be made from material such as aluminum and even wood.
Aluminum alloys are a versatile, and cost-effective mold making material. Howard Precision Metals offers a wide range of aluminum products and extrusions for various industrial, manufacturing, and construction applications.
Blow Molding
Blow molding is a manufacturing process in which hollow shapes can be joined together. The parts, typically manufactured out of glass, plastic, and even amorphous (glassy) metals, can be made by one of three blow moulding processes such as extrusion blow molding, injection blow molding, and injection stretch blow molding. With glass blowing as the principle from which mold blowing is based, the molding process begins with a tube-like piece of plastic or glass with hole in the middle in which air can pass. This piece of raw material is referred to as a parison. First, the parison is inserted and secured into the mold. Then, air is blown into it, which forces the parison to take on the shape of the mold. Once the part is cooled and hardened, it is removed from the mold. Blow molding accounts for the mass production of plastic containers such as: soda bottles, take-out food containers, plastic cups, clam-shells, cosmetics containers, and many, many more.
Compression Molding
Compression molding is a manufacturing process well-suited for very large, basic shape parts, large and flat, or large and moderately curved parts like car fenders or rubber rain boots. This process begins with a pre-heated molding material, also know and a charge, being placed in an open, pre-heated mold cavity. Molding material can be in sheet, solid, or pellet form and is commonly fiberglass resin systems, rubber, and silicone. The mold then has a top force or plug member placed on top, which forces the charge into shape. The overflow material, known as flashes, is captured in overflow grooves. The parts are left in the mold until they are fully cooled and cured. Lastly, the parts are removed from the mold and the flashes are removed. Because this mold process wastes little material, compression molding is one of the most cost effective molding manufacturing processes.
Thermoforming
Thermoforming involves the heating of plastic sheet to a temperature that makes it pliable. The plastic is then formed to the mold’s shape by stretching into or onto a mold. Finally, the plastic is cooled to yield the finished shape. Both pressure forming and vacuum forming can be used to draw the sheet against the mold. These types of molds may be manufactured from aluminum or wood. Thin gauge thermoforming is primarily used in the manufacture of items such as plastic cups, lids, and containers whereas thermoforming can also be used to produce very thick material like dash panels and vehicle beds.
Rotational Molding
Rotational moulding, also known as rotomolding, is a process by which a heated hollow mold is filled with a charge of material. The hollow mold is then slowly rotated to allow the charge material to fully coat the walls of the mold. In order to avoid deformation of the part during the cooling process, the mold continues to rotate until the part has fully cured. This process is extensively used to create various types of plastic products with a seamless, hollow geometry. These parts may be as large as a tank designed to carry tens of thousands of gallons of liquid or as small as a ping-pong ball. Similar to compression molding, this method is also very cost effective as it produces little waste and excess material can often be re-used.
Aluminum Alloys in Mold Making
Various aluminum alloy plates that are effective for the manufacture of molds include Alpase’s M-1 and M-5 mold plates and PCP’s Max 5 mold plates. The considerations to be made when deciding on the right aluminum alloy for your mold application include the geometry of the part, the type of resin used, the cycle time, the quantity, and the durability of the finished product. Popular alloys utilized in the creation of molds include:
- 7075-T651 plate aluminum alloy delivers excellent strength
- 7050 aluminum alloy is used extensively for production blow molds, structural foam molds, and injection molds. The thickness of these molds is limited to 8 inches or less.
- 6061-T651 plate aluminum alloy is used in large blow molds, compression molds, and low-volume injection molds.
- 6013 aluminum alloy provides superb strength, corrosion resistance, and weldability with a decent level of machinability and hardness. It can be relied upon to produce runs in the several hundred to a few thousand range.
- 2024 aluminum alloy is used for blow or structural foam molding and is reliable for short production runs.
- M-1 mold plate is an aluminum mold plate designed and developed specifically for the plastic and molding industries. It is an extraordinarily dense, dimensionally stable, high strength aluminum plate created especially for the growing high-temperature plastic and mold industries. M-1 lowers production costs through machinability advantages.
- MAX 5 aluminum mold plate is a wonderful option for larger rubber and plastic mold applications. This alloy is available in thicknesses from 4.0” through 42.5” thick with a mill lead time for delivery.
As a 100% aluminum distributor located in the Midwest, Howard Precision Metals is your premier source for aluminum products and extrusions. Through the combination of resources, skills, and experience, Howard Precision Metals will help you achieve your project goals, whether in the hydraulic, building construction, aerospace, machinery manufacturing, or pneumatic industry sectors.
For more information about how the team at Howard Precision Metals can serve your aluminum alloy molding needs, call today at 800.444.0311 or request a quote on our website.
