Month: February 2017

Resin Casting: Going from CAD to Engineering-Grade Plastic Parts

Plastics are so versatile; some of them are stretchy, while some are tough as bricks; some are crystal clear, and others come in any color you can imagine; some can perform in high temperatures, and yet others can stop a bullet.

Synthetic polymers play a role in almost every single commercially manufactured item on the planet. Plastics are not just ubiquitous, but extremely versatile: some of them are incredibly stretchy, while some are hard as nails; some are crystal clear, and others come in all colors of the rainbow; some can survive extreme temperatures, and yet others can stop a bullet mid-flight.
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From Pest to Bioplastic

Using a natural component to make plastic is nothing new, but using animal matter is a whole new level of creativeness. There is more than one person looking into making plastics out of animals, specifically other marine life.

The Chinese mitten crab, an invasive species from East Asia, gets its name because it looks like it’s wearing a pair of furry mittens on its claws. But it’s not so cute. The crab negatively impacts native wildlife in Europe and the U.S., where it’s labeled an “injurious species.”
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Plastic Injection Molding Process

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The plastic injection molding process is adaptable, making it versatile enough to produce anything from a simple plastic cup to car and laptops parts. While there are some alternatives to injection molding – like 3D printing and spin casting – injection molding remains the most reliable way to produce plastic goods. Because of this, injection molding is still the technique most often used to produce plastic goods in the 21st century.

But what is injection molding exactly? What does the typical injection molding process look like? And what exactly is it that makes injection molding so much more adaptable (and hence more versatile) than other options?

What Is Plastic Injection Molding?

Plastic injection molding is a technique used to shape plastic in the form of the object you’re aiming to produce. During the injection molding process, thermoplastic polymers are injected into a mold cavity. To do this, pellets of a material are heated so they can be injected into the cavity in a liquid state. This hot liquid is then left to cool in the mold so the part can properly set. Once one part is ejected from the mold, another cycle can promptly begin.

Although injection molding can also be used for metals and glass, it’s a particularly popular production process for manufacturing plastic parts.

The steps in an injection molding process cycle include clamping, injection, cooling and ejection.

During clamping, the injection mold is prepared for a cycle by tightly clamping the two halves that form the mold cavity into place. This ensures that the molded part will have a smooth appearance and ideally the molded part should have almost no line where the different halves came together, as this shows that the mold might not be clamping tightly enough.

Once the mold halves are clamped together, the mold is ready to form a part. Before the polymer is injected into the mold, the pellets are heated to form a liquid. The liquid polymer is then injected into the mold through a nozzle. This is the injection stage of molding process, which is the second stage in a four stage cycle.

Next, the part is left to cool in the mold for a predetermined amount of time. The cooling stage can take anywhere from a few seconds to a few minutes depending on the polymer being used to produce a part. While some polymers need hardly any time to cool at all, others can take a few minutes. It all depends on the part being produced.

Once a part has cooled, the injection mold is opened and the part is ejected from the mold. The mold will clamp again and prepare for its next cycle.

Because manufacturers know how long the cycle on their molds are, they can accurately predict the amount of parts a mold will produce every hour. This helps manufacturers know exactly how many parts they’ll be able to produce every day, week and month with a fully functional mold.

Why Is Plastic Injection Molding So Popular?

As mentioned above, plastic injection molding is a very predictable process. This predictability also makes the process dependable, as injection molding companies will know exactly how many parts they can expect from every mold they own.

Based on the amount of parts each mold is able to produce, manufacturers can calculate how many molds they need to in order to produce enough parts for their production line to operate at its intended capacity.

It should also be possible for manufacturers to estimate the amount of parts they can produce with a mold during its entire lifetime, making it easier to calculate whether or not a mold will generate enough income to cover its own costs with profit added.

All this is fine and well, but for injection molds to be reliable and predictable they must be maintained according to a maintenance schedule.

Unfortunately, some manufacturers run their molds till they break down. This might be because they’re just inherently stingy, but often times it was recommended to them by financial advisors in their company. The problem is that finance and engineering are worlds apart.

As mold manufacturers, we know that regular mold maintenance can extend the lifetime of your molds and help them operate optimally at all times. Yes, mold maintenance is an expense, but it’s not one you can cut to save money. If molding plastic parts is an integral part of your business, the condition of your molds in undoubtedly important. Cutting on maintenance by working molds till they break down will hurt your company.

It’s ironic that predictability, which is one of the advantages of injection molding, isn’t considered by many molders when overworking their molds. Fact is, a mold that works till it breaks down can’t always be repaired, and the halt in production from the broken mold can’t be scheduled because you won’t know for certain when it will break down.

When looking at it like that, it’s hard to understand why working a mold till it breaks could be considered a viable way to save money. Perhaps it’s time that molders look further into the issue of maintenance to establish what really works best.

But apart from the predictability of plastic injection molding, the process is also very versatile. Thousands of polymers can be used for injection molding purposes, and injection molds can be adapted for different uses. Which is why the process is as effective for the automotive industry as it is for the medical industry. With micro-molding technology, injection molding can even produce even very small parts with surprising accuracy.

To conclude, injection molding is popular mainly because no other manufacturing process allows manufacturers produce a lot of parts in a relatively short amount of time, all while maintaining the desired level of part integrity.

What are eco-plastics?

When thinking of plastic “ earth friendly” isn’t on the list. From trash pollution, to length of deterioration, to recycling; plastics aren’t normally in on the favorable side of the earth talk. If we could fix the problem at its source, what plastics are made of, we can make them more eco-friendly. But how something would last in a situation where the plastic is being used for long periods, and will be outside a lot in the weather such as automobiles?

Most of us have understood for years that plastic is an environmental no-no. It’s fuel based, requires lots of energy to produce and it clogs up landfills for what might as well be forever. It’s difficult to imagine a plastic we can buy without guilt. And whether eco-plastics fit that bill depends on how “green” you want to be.
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Can we ever replace plastic?

In our lives we are surrounded by plastics; phones, car parts, water bottles, food containers, computers, honestly almost everything has some form of plastic component. With almost everything we touch being made out of some form of plastic or another, it’s hard to imagine our lives without plastics. Will we ever be able to get rid of our plastic dependence?

The downsides to plastic are certainly no secret. For starters, it’s often a nonbiodegradable, petroleum-derived product. Factor in toxins, wildlife endangerment and difficult recycling, and the plastic industry has quite a public relations problem on its hands. But that’s only half the story.
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Identifying Unknown Plastics

Even if the plastic you have isn’t labeled which type of plastic it is (though it should) there is ways to tell what type you have. Though the variety of possible plastic materials is essentially infinite, the familiar SPI recycling codes are the typical way to identify plastics. Knowing what plastics are used in other projects can help you find the plastic you are looking for in your own project.

The burn test, as it’s known, correlates a plastic sample’s composition with a set of observable properties including…
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Are food-based plastics a good idea?

When thinking of plastics and food we normally think “Plastic food container” while “Plastic making material” is probably the last thing on our minds. Using foods to produce plastics will help the eco friendliness of plastics. But how would such plastics preform in the long run?

Food-based plastics, made out of everything from corn to sugarcane, have rapidly grown in popularity over the past several years. Packaging materials, gift cards, cell phone casings — all can be made from these eco-friendly materials.
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What is the World’s Strongest Plastic?

Defining what the strongest plastic is, isn’t as cut and dry as you might think. But know what the “strongest” plastic is, based on a few things, can help you decide what plastics you may need for your plastic injection molding prototype.

It’s a simplistic question, possibly even naive. Put it to a chemical engineer or a materials scientist, and she or he will almost certainly not come back with a single answer.
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Injection Molding Machine Tending

Many companies have made the change to have robotics tending machines over a worker. Is there more of a reason aside from increasing profits? Robotics is something we rely on so heavily in today’s world, they make things we do better.

Since machine tending is not specific to CNC machines, we thought it would be great idea to look at some other manufacturing tasks that can be done using machine tending, like, injection molding.
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