Call 603.742.1581

Compression Molding: Forming the World Around You

Home » Blog

May 3, 2012

Compression Molding: Forming the World Around You

Compression molding is one of the most common processes used to mold plastics into a usable form, and it is also one of the most cost effective. Most often, compression molding is used to create a wide variety of parts and components ranging from compression molded car parts to medical products.

The first commercial foray into compression molding was in 1847, when the technology was used to create hand mirror frames and other domestic products. Later, the then primitive process was completely overhauled in the 1930’s when the first compression molding machine was created giving way to increasingly more modern machines and eventually leading to the level of speed, efficiency, and precision we expect from products today.

This technology of manufacturing is especially used when the density and material type required must remain uniform throughout the part. It will also have no moving parts, and will be molded all at once.  However, many small compression molded parts are often assembled together to form larger machines – like automobiles.  For the right industries, compression molding has proven that it is one of the most effective and efficient methods for creating certain products, and this has remained true for years. Some examples of compression molding parts and products include everything from ash trays and appliance knobs to vehicle panels and radios.

In basic terms, compression molding is  a simple processwhere plastic is heated and pressed into the required shape. Compression molding is typically done with thermosetting materials. While thermoplastics remain capable of melting when subjected to heat, thermosets are used because they do not soften with heat and retain their molded form. In compression molding, technicians use a hydraulic press to force the liquid plastic material into a mold shaped like the desired product. When the material inside cools, the mold is removed from the mold in the proper shape, excess plastic is trimmed away, secondary operations and finishing are completed, and the part or product is either ready for sale or use as a component in a larger product.

Compression molding comes with a variety of advantages ranging from low cost moldings and lower labor costs to less shrinkage and a high level of repeatability. Additionally, due to the extremely small amount of material that gets wasted, manufacturers can afford to use more expensive plastic compounds in their products.  Some of the downsides to compression molding include somewhat lower product consistency than other methods, uneven lines, and less flexibility when it comes to the depth of the mold. Regardless, for certain parts and products compression molding is a fantastic technology that has been and will continue to be a stable in the industrial community.

Filed under: compression molding — admin @ 6:29 pm

January 30, 2012

Custom Plastic Thermoforming: Every day, Everywhere

It’s funny how many things we use every day. From the computer you’re reading this on to the car you’ll drive when you go to the store. Things surround us, but we seldom wonder how they came to be. You won’t be surprised that many of these things are plastic, and a fair majority of them have come to be because of custom plastic thermoforming process.

You might not realize it at the moment, but plastic thermoforming impacts your life more than you might think. In fact, throughout your life you can trace the impact of plastic thermoforming. Don’t believe me? Read on. First consider where you were born. No, not the city or the state – but the room you came into kicking and screaming. Chances are you entered this world into a brightly lit, sterilized, and hectic delivery or operating room. Inside that delivery room were plenty of surgical implements and medical devices. Many of them (like the medical tray the doctor used) were created with plastic thermoforming.

Years later, after hundreds of diapers, baby formula, and many sleepless nights for your parents, you might have gotten involved in youth sports. Whether it was soccer, football, rugby, or high-stakes cage fighting (let’s hope not), the protective equipment that kept your face intact, your teeth in your head, and all of your body parts in working order was likely custom thermoformed in a manufacturing plant, using special polymers, custom molds, specialized thermoforming equipment, and a variety of finishing methods.

At some point, after your youthful days you inevitably found yourself in the adult world. Chances are, you moved into your first home, bought plenty of thermoformed plastic products, bought a car (with a custom thermoformed interior), and filled your cupboards with reusable thermoformed plastic food containers that rarely could be paired with their matching tops.

At this point, it’s not my goal to be morbid or depressing, but one day you might find yourself back in a hospital. You know, the whole “circle of life” aspect of life. Chances are when that happens (and hopefully, it won’t happen for a very long time) you’ll find yourself once again surrounded by custom thermoformed products like medical trays and thermoformed bedpans. At that point – you shouldn’t feel bad if you don’t give all of the plastic in your life a second thought, just don’t miss the bedpan.

Filed under: plastic thermoforming — Tags: , , , , , — admin @ 3:11 pm

January 15, 2012

The Simple Science Behind Pressure Forming

Pressure formingis a technology you frequently take advantage of, and it can be explained in a number of ways. First, you might consider the simple definition: that pressure forming is the (relatively) simple science where heat and pressure are applied to plastic to form a product. However, the more complex definition of pressure forming reminds us that, technically, all thermoforming (except mechanically bending and shaping a material) uses pressure, and should be considered pressure forming.

A simple diagram of the pressure forming process

The more complex definition of pressure forming explains that pressure forming is used when the forming temperature of the sheet is too stiff to form to the mold. When this occurs, air pressure is used on the free side of the plastic sheet and the vacuum to more effectively mold the plastic to the mold.

Thermoforming (or pressure forming) is a relatively generic term for a large number of forming technologies and is one of the oldest methods of forming two (or more) pieces of plastic. While modern pressure forming is separated from early thermoforming by years and years of innovation, a brief history of thermoforming can never hurt.

According to most sources, early thermoforming dates back to the 1870’s in the USA, when John Wesley Hyatt (largely considered the father of modern plastic processing) and Charles Burroughs rolled thin skived sheets of celluloid plastic into tubes. They then inserted these tubes into steel molds and heated them with steam under pressure. Using this method of heating, the steam softened the celluloid sheeting and eventually forced it into the mold shape. The molds were then removed and cooled in water to harden the plastic.  The rest of the process is extremely similar to modern pressure forming, Hyatt and Burroughs simply opened the molds, removed the parts, and trimmed them to the necessary size. Back then, typically pressure formed parts included shaped bottles, mirror cases, baby rattles, and more.

Two Step Pressure Forming

Typically, the pressure forming process is a two-step one. First, the sheet is drawn against the mold surface by expelling all the air from the mold cavity with a vacuum. Next, a metal box called the pressure box is used to create a seal between the sheet and the mold service. After the seal is created, air pressure is used to force the plastic sheet into the mold, copying its surface. Once the part has cooled, the air is gradually allowed to bleed out, the pressure box is unclamped from the sheet, and the part is removed.

Twin-Sheet Pressure Forming

Because of the widespread use of pressure forming to create an extremely wide variety of parts and products, a number of processes have been developed and perfected to produce different results from the pressure forming process. Twin-sheet pressure forming is one of those processes, typically used to form hollow (or partially hollow) plastic parts. While the process is relatively similar to simpler pressure forming processes, due to advancements in technology twin-sheet pressure forming has become a cost-effective alternative to blow molding.

These are only two of the many types of pressure forming processes. Check back frequently for more articles on pressure forming, what it’s capable of, and how it can be accomplished.

Click here for more information on pressure forming

Filed under: pressure forming — Tags: — admin @ 9:32 pm

January 12, 2012

Get Your Feet Wet in The World of Plastic Manufacturing: Compression Molding 101

Imagine the rain is falling in streaks. Not drops, not buckets, but a long and steady sheet of water that falls to the ground, almost instantly planting stream that spout forward into a brown muddy torrent, carrying rock, stone, and sediment wherever the deluge cares to take them. You look out the window, and the first thought you have – to go back to bed and listen

Leo Baekeland

Leo Baekeland, the "Father" of modern compression molding

to the rainfall – is the last thing you can do. Naturally, you do the only thing you can on a day like this. You step into your rain boots and you walk into the wet, wet world.

You think to yourself, “Wow, rainboots are an amazing thing!” and in that very moment, without even realizing it, you’re thankful for a little area of manufacturing we call compression molding. Compression molding is a method used to mold a preheated plastic polymer. To do so, the material is first placed in an open heated mold. This mold is then closed, pressure is applied to force the material into all the nooks and crannies in the mold, and the pressure and heat are maintained until the material being molded has completely cured hardened.

The first recorded use of compression molding was by Leo Baekeland in 1907 using phenol-formaldehyde resin. The equipment was primitive and it would continue to be for another 20 years when a crude compression machine was invented and the modern compression molding process was born. When this happened, the original resin used was called Bakelite, in honor of the creator of the process. In the mid 20thcentury, the invention of the automobile and the rise of companies like Goodrich and Goodyear tire continued to spur the rapid improvement of compression molding, gradually leading to better materials, better machines, and more reliable compression molded products.  Eventually this lead to compression molded products being reinforced with materials like glass fiber, paving the way towards the high-tech resins used in all sorts of materials today.

compression molding plastic

A simple diagram of the compression molding process

Compression molding has become a wildly popular manufacturing technique because of the way it can quickly and cost efficiently mold large detailed parts without wasting material. This not only makes it ideal for businesses hoping to create a large volume of products (like rain boots) but it is also highly beneficial when a business is using expensive compounds that they can’t afford to waste. Compared to other molding techniques, compression molding is also capable of producing much larger shapes, making it a cheap and versatile technique for manufacturing many of the products we use every day, like rain boots and car parts.

From protective packaging and case inserts to protective padding and insoles for your footwear, compression molding can be found just about everywhere. So next time you pick up a plastic product you might otherwise take for granted – think about its history. How did it come to be? Was it the result of Leo Baekeland’s experiment so many years ago?

Filed under: compression molding — Tags: — admin @ 9:13 pm

January 5, 2012

Foam: Protection When You Need It.

Protection: it’s a concept that applies to so much, yet we tend to think so little of it, unfortunately, until it’s too late.  Virtually everything at some point needs protection. When you enjoy the winter by taking to the slopes, your head and your body need protection against the elements and any potential accident you could have. In the same way, when you ship a gift to a friend or relative, you protect it so it arrives in one piece. Or when a doctor uses a delicate medical device to help a patient, it was originally protected and secured so it would be ready for use when it was needed. Needless to say, protection is an important thing, but one of the technologies that ensures protection in so many ways is often overlooked. That technology is foam molding.

There are two typical processes used when it comes to manufacturing foam products. Today, we will focus on compression molding. With compression molding, the material is usually preheated and placed in a mold cavity, which is then closed before pressure is applied and the foam material if forced into all of the molds necessary nooks and crannies. This allows for extremely accurate and detailed parts for just about every industry.

The material typically used for compression molding is a thermosetting resin, added in a partially cured stage as either a granule, preform, or putty-like substance. The advantage here, as opposed to other manufacturing methods, is that compression molding is capable of intricately molding large and small parts with a high degree of precision. At the same time, compression molding is also cheaper than many other methods, without wasting nearly as much material as other processes. This makes compression molding highly favorable, especially when expensive compounds are being used.

Foam molding was pioneered primarily to manufacture parts to replace metal parts in various applications. For other applications, it was used to quickly and cheaply form foam and plastic to be used for protection, covering, shipping, containment, and more. When compression molding is not used to replace metal parts in various applications, it is frequently used to create soft protective coverings and inlays such as case inserts for fragile part and products.

While it might not be something you typically consider, without foam compression molding – our world would indeed be different. For example, imagine you had to receive an emergency operation in the E.R. The container that shipped the delicate medical instruments you relied on probably used foam compression molded foam for protection. Or, maybe you’re one of the many people that feel a whole lot better with comfortable in-soles in your shoes or boots? Those are also the result of custom contour cut compression molded foam. You could find numerous examples of compression molded foam in your day to day life, these are just a few – but next time you feel something soft, think about the many ways compression molded foam might be helping or even protecting you every day.

Filed under: foam molding — Tags: , — admin @ 4:29 pm

December 30, 2011

A Lesson in Plastic Vacuum Forming and its Role in Your Life

Time for a history lesson (and a bit of a physics lesson, too). But before you start rolling your eyes, thinking to yourself “but I’m donewith school,” think again. How often do you use a vacuum? Maybe you’re a neat freak that needs everything clean, or maybe you’re afraid of the vacuum as much as a small toy dog. Either way, when you get thinking about the vacuum, you’ll start to learn more and more about our world and how it comes into play to change our lives.

A basic illustration of the vacuum forming process

The encyclopedia defines a vacuum as a “space that is devoid of matter such that its gaseous pressure is much less than its atmospheric pressure.” When a vacuum is created the difference in air pressure creates suction, which effectively manipulates the atmospheric pressure so it pushes air into the area of lower pressure. Thought of practically, when you use your vacuum cleaner at home – the air is actually being “pushed” through the carpet and into the machine by atmospheric pressure. While vacuums range in power from the simple vacuum in your closet (a coarse vacuum) to the world-crushing force of outer space (with an atmospheric pressure virtually nothing could survive), the concept remains the same.

So then you might wonder ,“How do I actually use vacuums beyond cleaning my floor?” You might not directly use vacuums every day (unless you’re a superhero that can manipulate atmospheric pressure with your mind) but you do take advantage of vacuums. You do this by using vacuum formed products.

Vacuum forming, which is also commonly referred to as vacuuforming, is a method of thermoforming that forms a number of the products and materials you use every day, and it does so by (essentially) combining a plastic sheet, a powerful vacuum, and a mold. Thermoforming is one of the oldest and most common methods used to process plastic materials and form products that play major rolls in all of our everyday lives.

With a history dating back hundreds of years, vacuum forming was first used (sparingly) in the mid-twentieth century. However, once plastic was more readily available in the 50’s, plastic vacuum forming experienced a surge in popularity in which many simple products like lids, containers, and food packaging was manufactured faster and more economically using the process. Today, with the creation of advanced plastics and polymers as well as more effective heating and vacuum processes, the footprint of plastic vacuum forming can be seen everywhere, from the simple products in our kitchen to thermoformed plastic components used in the aerospace industry.

The vacuum used in plastic vacuum forming uses a vacuum much stronger than the one you use in your home to exert extreme pressure on a heated sheet of plastic, this quickly and effectively molds and stretches the plastic into the mold shape created by the manufacturer. Finally, the vacuum formed plastic is cooled, trimmed, and finished to create a useable product. Every day, plastic vacuum forming is used to create all kinds of products and everyday conveniences like plastic chairs, toys, car interiors, medical products, and lunch trays.

So Next time you break out your vacuum cleaner to quickly and effectively harness the power of the atmosphere (okay okay, that might be slightly over-the-top) think about what can be done with vacuums every day and how manufacturers use them to make so many conveniences possible. From the interior of your car or the protective packaging on your electronics to the thin plastic that keeps your medicine fresh and safe, it’s all the result of plastic vacuum forming. Isn’t the marriage of science and ingenuity a beautiful thing?

Filed under: vacuum forming — Tags: , , — admin @ 5:05 pm

December 22, 2011

Medical Device Packaging: Protecting the Supplies You Depend On

In a previous article, I mentioned the fact that you will find plastic products as a part of your life no matter where you are. You may think it trivial, but it’s true – and it’s something worth thinking about. For example, when you entered the world into that brightly lit delivery room – chances are you were surrounded by plastic medical fabrications. From the protective packaging for the medical devices used by the doctors to the protective packaging used to keep your medicine fresh and safe, chances are that medical packaging changed the way you came into this world, and made it safer than the process was for generations past.

However, it goes even deeper than that. Medical device packaging is used every day to make medical procedures safer and more effective. Think about all of the hospital dramas you may have seen on television. In just about every one, you saw a group of at least 2 doctors and 3 nurses hustling a patient with life threatening injuries to the emergency room. As soon as they get there, they can’t be fumbling with the packaging.

Or, think about the young asthma patient rushed into the E.R. in critical condition, unable to breath, turning colors a person should never turn, and slipping closer and closer to unconsciousness. When the doctor opens the camera used to find the cause of the patients blockage, he can’t afford for it to be damaged or malfunctioning because of faulty storage or packaging.

Or, think about the gunshot victim brought into the hospital late at night. With allthe monitors running and the machines beeping, doctors and nurses are feverishly opening packages of supplies needed by the patient’s body. If they are hard to use or cumbersome, precious seconds are lost that could otherwise be used to save the patient’s life. In these ways (and many others), medical device packaging directly affects the life or death scenarios in a healthcare setting.

So as you can see, medical packaging is a seriously important part of life (and I mean that in the literal sense as well). Beyond making the job of nurses and doctors easier, it simply goes to show the ubiquitous nature of plastic in our lives, how widespread it is, and how much we’ve come to depend on in a seriously wide variety of situations.

As you go through your day, or even the next couple of hours – make a mental note of all the times you use plastic. Or next time you go to the doctors, consider all of the medical packaging you see and imagine how  it might impact the quality of care you’re receiving in a positive way.

 

Filed under: medical device packaging — Tags: , , — admin @ 9:58 pm

Medical Device Packaging: Making the Difference

The overhead lights illuminate every nook and cranny in the operating room with a harsh white light. “Iodine” the surgeon announces, and his attending nurse hands him an iodine soaked swab without wasting a second. Like a well choreographed dance, she reaches for the tool she knows the surgeon will need next, precisely as he announces “trephine” and the process begins to methodically remove enough skull to effectively drain an epidural hematoma, reduce the pressure on the brain, and prevent coma or death.medical device packaging
(more...)

Filed under: medical device packaging — Tags: , — admin @ 9:18 pm

December 19, 2011

Custom Plastic Thermoforming: You Take Advantage of it Every Day, but What is It?

Every day you take advantage of plastic thermoforming in large and small ways. For example, if you were to go into your kitchen and open your silverware drawer, chances are there would be a tray there. If you’re the organized type, that tray probably has 4 or 5 raised partitions to separate spoons, forks knives, and other miscellaneous forms of cutlery. That tray was thermoformed. Sure, unless you are truly passionate about cutlery trays, it’s likely not a major part of your life – but it does make it easier.
(more...)

Filed under: plastic thermoforming,Uncategorized — Tags: , , — admin @ 9:52 pm

December 12, 2011

Under Pressure: Pressure Forming and You

As the famous 80’s song goes, when things are “under pressure” they tend to change. But while pressure can so frequently be seen as a negative thing, it doesn’t have to always be thought about that way. Pressure is used as a positive force more frequently than you may think. Consider for example pressure forming. While you may hardly (or never) think about pressure forming, it has undoubtedly  had an impact on your lift, whether you know it or not.
(more...)

Filed under: pressure forming — Tags: — admin @ 9:49 pm

Older Posts »