Plastic molding: The complete guide
To understand plastic molding, we will need to take a more practical approach. Think of it as a process that turns molten or raw plastic materials into molds. A rotational molding company will then use the molds to create a finished plastic product. Depending on the type of process used, for example, plastic injection molding, various ranges of pressure and heat are applied.
In this article, we will take an in-depth look at plastic molding to understand why it has become quite popular. You will also get a chance to see our projects and learn what a plastic injection molding company does. If you have been looking for the complete guide to plastic molding, you have come to the right place.
Plastic molding: When it all began
In the 1800s, ivory billiards balls were the commonly used material. However, John Wesley Hyatt was tasked with finding a way to make these billiard balls more uniform and efficient. John came up with a brilliant invention that let him inject celluloid into a mold, thus creating plastic billiard balls.
Four years later, John and his brother invented the first plastic injection molding machine. It was a rudimentary machine that worked like a hypodermic needle. Creating small objects such as hair combs and buttons using the machine was fast and straightforward.
After years of improvement and advancement in technology, James Hendry invented the screw injection molding machine. The new technique ensured that the molding process was simple and straightforward, thus increasing productivity.
Different types
Six different plastic molding techniques help create the various plastic products that you love. Rotational molding companies will use any of the techniques depending on their level of expertise, budget, and resources.
1. Compression molding
Compression molding is a simple plastic molding process as its name suggests. A plastic material gets heated and placed into a heated mold. Pressing it ensures that a company can design whatever shape they need. With compression molding, the plastic has maximum strength thanks to the heating process.
Now, compression molding helps when you need to replace any metal parts with plastic parts. Automotive companies, for example, use compression molding because they get durable parts at an affordable price.
However, note that compression molding is not quite common among companies. The initial cost is relatively high, and the process is somewhat complicated. Companies intending to produce large quantities can get the maximum gains from using this type of molding.
2. Thermoforming
Thermoforming involves a simple vacuum forming process. The first step is heating plastic sheets, then creating a custom shape in a mold. The final step is trimming to ensure that you get the desired shape.
As stated earlier, a more practical approach ensures that you grasp what we are talking about. See our products to help you understand how thermoforming works. It is commonly used in the production of containers, disposable cups, trays, blisters, and lids.
You will need about eight weeks before you can get the thermoform mold ready for production. On the other hand, the costs will depend on the size of the products you need to produce. In this molding process, large products will need more capital when compared to small products.
3. Blow molding
Blow making is a simple and straightforward plastic molding of creating hollow, thin-walled plastic parts. It is a great technique that lets a rotational molding company create plastic products with uniform wall thickness.
However, note that blow molding is efficient when the shape of the product is not essential. The entire process is similar to that used in glass blowing. Different machines heat the plastic while injecting hot air. The plastic gets blown into a mold before it is cooled and ejected.
See our projects, including plastic tanks, bottles, drums, and fuel tanks, to understand the common uses of blow molding. It is an economical and fast way of creating hundreds and thousands of plastic tanks or bottles.
4. Extrusion Molding
Extrusion molding is quite different from all other types of molding because the plastic does not take the mold shape, but instead takes the die’s shape. You get a product with uniform cross-sections and continuous length.
Note that the shape of the die dictates the shape of the final plastic product. Some typical applications of extrusion molding include PVC straws, pipes, and hoses. Understand that the listed products need a consistent shape along their entire length.
Although the cost of extrusion molding is low, the nature of the process limits the products produced. Only use this technique when you plan to create a limited number of plastic products.
5. Rotational Molding
You will notice that some rotational molding companies refer to rotational molding as roto-molding. Generally, it is the process of creating large hollow products by placing liquid resin into a metal mold. The product is placed in an oven where it is rotated until resin coats the mold’s inside.
You get an evenly walled product when using this molding process since the constant rotation generates centrifugal force. You can then remove the hardened plastic once the mold cools down. Several molding companies use this type of molding technique since excess material is reused.
See our projects to get a full picture of the application of rotational molding. Some of the products include plastic tanks, car parts, bilk containers, pet houses, road cones, playground slides, and marine buoys.
6. Injection molding
Plastic injection molding is quickly becoming the most popular manufacturing process. A plastic injection molding company gets to mass-produce high-quality plastic parts at a decreased cost. We all need to agree that meeting high market demands at a lower price is a cause of celebration.
Injection molding basics includes five significant parts: the hopper, sprue, runner, barrel, and the mold. The raw resin is added onto a hopper and fed directly into the barrel. Heat and compression melt the raw resin to create the mold before hot plastic is injected into the barrel. The heated plastic gets cooled, thus creating the original molded part.
Repeating the process rapidly ensures that a plastic injection molding company can create high volumes within a short period. However, note that a bit of time is required to develop the precision molds. The trick is getting the precision molds right because they create a base for rapidly producing more products.
Why most companies choose plastic injection molding
Scalability
As stated earlier, the injection molding basics are quite simple. It is, therefore, more comfortable to quickly dill large orders once you get the precision molds. Companies can quickly scale up production without having to incur any extra costs. The good news is that the more a plastic injection molding company produces, the lower the production costs.
Repeatability
With plastic injection molding, you get to produce a reliable and consistent product with minimum errors. Once you get the injection molding basics right, you can consistently provide high-quality products without changing any variables.
Reduced waste generation.
Thermoplastics are among the conventional injection molding materials. It can always be reused, meaning that companies have reduced waste. The thermoplastics are melted down and reused to create other parts. Common injection molding materials also include thermosets, which are used in specialized processes since they cannot be reused.
Detailed features
Since injection molds are subjected to high pressure, companies can easily add a lot of details to the different designs. It is also possible to create intricate and complex shapes that could be expensive or complicated when done by other methods.
Enhanced strength
With plastic injection molding, companies use fillers that increase the density of the plastic. Increased density translates to more strength once the molding is complete. It is all about creating a high-quality product at a reduced cost, and injection molding gets you exactly that.
How to avoid the common mistakes in plastic injection molding
Injection molding is a seamless process when it comes to mass production. However, it also requires specialized skills and trained personnel. Most companies will run into several problems during the initial stages, which is quite reasonable.
The problem with mistakes is that they create a big dent in manufacturing costs. Some common errors include short shots, flow lines, surface declamation, sink marks, weld lines, vacuum voids, jetting, and burn marks.
All the above common mistakes are avoidable once you choose the appropriate plastic molding technique. As a plastic molding company, you need to ensure that you use the proper design and tools during the manufacturing process. Work on improving the design of the precision mold to help you get an automated manufacturing system going.
Conclusion
The plastic molding process ensures that a plastic injection molding company provides quality products at a cheaper cost. Understand that selecting the right type of rotational molding will ensure that you have better yields and higher productivity. You could always incorporate different techniques when you need to introduce unique products into the market.
Conduct in-depth research to ensure that you pick the right molding technique for your company. Think about the products you are creating, the production quantity, available capital, and level of expertise. As stated earlier, the initial installation stages can be quite extensive. Have a laid-out plan before venturing into the plastic molding business.