Month: March 2017

How to Choose the Proper Plastic

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If you’re looking to become a plastic molder, the two main things you should consider are your plastic injection molds and the materials you’ll use to create parts. Before setting out to have your mold designed and made by Quality Mold Shop, you should consider the purpose of the part you plan to create.

Choosing the Right Plastic for the Right Job

Different plastics have different properties, making some more suitable for certain jobs than others. If you take a look around you, noticing different things made from plastic, you’ll notice how similar plastics are always used to make similar products.

Your laptop case, for instance, will always be made from a hard plastic rather than a soft one. If you examine the properties of the plastic used to make laptop cases, you’ll notice that the plastic doesn’t really give way or bend easily. It’s hard, yet it’s durable enough to not break or crack easily if it gets a light knock. The lid on your lunch box, on the other hand, isn’t hard like that. It’s a soft plastic that easily bends and gives way. This can help it to stretch a little over the lunch box container, creating a stronger seal.

If you used a hard plastic to make a lunch box lid, it wouldn’t stay on the container as securely. And if you used a soft, bendable plastic to make a laptop case, it wouldn’t protect the hardware inside the computer from light knocks.

In both cases the plastic used was picked carefully based on the function of the part that’s being made. This is what makes plastic such a popular material for manufacturing, its versatile. But that versatility comes in the form of different polymers. After looking into plastic injection molding and different types of plastics available, you’ll see that laptop cases are most often made of plastics like ABS (acrylonitrile butadiene styrene), while lunch box lids are made from materials like polyethylene.

Practical Considerations

Of course the ultimate function of a molded plastic part will be an important consideration when choosing the right polymer for the job. But how will you know what factors to consider in order to choose a plastic with the right properties?

Here are some of the practical things to consider when choosing what material to use for your plastic parts.

Price

Some polymers are just more expensive than others, so the market value of your final product will have a big impact on your choice of polymer. The raw material could cost you anywhere from less than a dollar per pound, to as much as $50 dollars if you need a specialty material. So obviously the possible price fluctuation is huge.

And it goes without saying that you simply can’t use a polymer that costs $50 per pound as a raw material, if your final product will requires a pound, but will only cost $40. That’s an oversimplified example, but it drives home the point that cost is vitally important when choosing what plastic to use.

Durability

Some products don’t need to be very durable at all, while other products are expected to last as long as a lifetime. You’ll know how durable you expect your product to be before having a mold made, and so you should choose a plastic that can live up to these expectations.

People don’t expect disposable plastic cutlery to be particularly durable, but a reusable plastic cup should be made of plastic that won’t easily crack like its disposable counterpart.

Another essential part of choosing a durable material is its resistance to temperature. A simple plastic like polyethylene isn’t very temperature resistant. So while it’s a good plastic for everyday objects, it won’t perform well under somewhat more extreme temperatures. While hot conditions isn’t good for the material, cold conditions also negatively affect its plasticity. Meaning that a part made from polyethylene can actually break or shatter below freezing point, losing its ability to flex.

Part Design

The shape of the part you want to make will influence the polymer you choose. Simple shapes can be made using almost any polymer, but if the part you want to mold will have more holes, depressions, ribs and gussets, you have to pick your polymer more carefully. Not all plastics can be as easily shaped as others.

And while aesthetics isn’t necessarily the most important thing to consider, it’s also something that will influence your decision. Getting a plastic with high gloss, or one that will be good for making a part with a matt effect might be important to you.

Flexibility

Some parts are meant to be able to bend a lot without cracking, while others are made not to bend. It goes without saying that any part that will have to flex a lot, should be made from a plastic that can handle this kind of tension without snapping and breaking. But some parts are meant to stay securely in place under pressure without flexing or giving way, and these parts should be made from harder, yet durable plastics.

The best way to know what plastics will be a good fit for your project is to talk to professionals. Follow the advice from both the engineers working to make your molds, and a chemical engineer. After all, the best way to get it right the first time is to not base your choices on guessing games, but to rely on sound professional advice.

Want to know how to source automotive plastics? Looking for a plastic molder?

How to Design the Perfect Plastic Part

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Used to deliver top notch exactness parts everywhere volumes and low costs, plastic injection molding offers adaptable answers for a scope of uses.

While this procedure offers a few one of a kind advantages over other generation forms, the achievement of an injection shaped part relies on upon its mold; with the correct outline, durable, quality plastic parts can be made reliably and effectively. Poor outline can prompt to expensive and tedious preparing botches.

With a specific end goal to advance the viability of high-volume injection molding and boost the exactness and nature of your parts, a few key plan components ought to be considered before proceeding onward to creation.

Divider Thickness

You can reduce — and even eliminate — most injection molding part defects by taking the time to lay out a smart wall-thickness design. The key is to ensure that the thicknesses of all walls are as uniform as possible, as molten plastic will seek out the path of least resistance (in this scenario, larger wall areas), leaving smaller wall areas potentially unfilled.

Rib Design

Ribs are utilized to fortify the quality of a high-volume injection molded part. Ribs ought not surpass 70% of your parts divider thickness, be that as it may, nor should they fall under half of divider thickness; both situations can bring about soaking in the surface of your part. Additionally, make sure to give careful consideration to the tallness of the ribs, their area, and their level of draft for simplicity of discharge.

Boss Design

Bosses are part features serving as one component of a larger product that requires assembly. During assembly, bosses can serve as anchor locations for screws, pins, or other fasteners. These components have width and height recommendations similar to those of ribs. Pairing bosses and ribs, especially in corners, can strengthen your part and significantly reduce chances of sinking.

Corner Transitions

In high-volume plastic injection molding, parts with outrageous or unexpected geometric elements can be inclined to defects — liquid plastic streams in the easiest course of action, and brutal points can obstruct that development. At whatever point conceivable, all corners and divider creases ought to be bended, with coordinating inside and outside spans. Smooth corner moves take into consideration better plastic stream.

Weld Lines

Weld lines — otherwise called weave or merge lines — happen when two plastic streams, or two areas of a solitary stream, meet. They happen most ordinarily around gaps or different hindrances, with the plastic stream isolating to pass them and afterward returning together a short time later. Each plastic infusion formed part has weld lines: the objective is to plan your part so weld lines happen in areas that don’t trade off your part’s quality or respectability.

Gate and Vent Placement

The gate of a large-volume injection mold is the point at which molten plastic exits the mold’s runner and enters the part cavity. Both the type of gate you choose and where you choose to place it can substantially impact your part’s quality. Vents, which allow air to escape from the mold as plastic rushes in, are similarly important; when positioned properly, vents can help minimize weld lines.

How do hybrids utilize eco-plastics?

The whole point of a hybrid is to be eco-friendly, so why would the manufacturers lean to more eco-friendly plastics? Of course that is easier said than done; what of the crash safety? There may finally be a breakthrough in the eco-plastics world.

With about 250 pounds (113 kilograms) of plastic in the average car, the auto industry is doing its part to fill the world’s trash heaps. When that average car outlives its usefulness, all that fossil-fuel-based plastic ends up in one of two places: either recycled into other plastic parts, releasing tons of carbon dioxide in the process, or spending anywhere from a few hundred to a few thousand years in the average landfill, where it proceeds to take up space and leach harmful chemicals into the air, soil and water supply.
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