What are the advantages and disadvantages of injection moulding? A lot of people don’t know that moulding is one of the most important parts when it comes to manufacturing plastic products.
It’s a process where molten plastic material is injected under high pressure into a complicated mould cavity. And although there are advantages and disadvantages to injection moulding, the main pro is that it’s fast in production and versatile.
Injection moulds come with a cavity but no core, which means that you don’t have to first create the shape and then create the cavity. The process is automated, and once you start the machine it will run on its own. This makes it great for mass producing products or creating several parts at once.
In injection moulding, mantles and cores can be easily changed out, meaning that you can make some parts unique for each part of a product. For example, if your product is a chair, then you could have one chair where the arm rests are different from another chair made of the same material.
This article will be discussing on what injection moulding is, the uses of injection moulding, injection moulding processes and the advantages and disadvantages of injection moulding.
What Is Injection Molding?
Injection moulding is the process where plastic material is injected under high pressure into a complicated mold cavity. When making your product, you will usually have a solid block of plastic that has been shaped and melted down.
After you have shaped the product, you will then insert the block of plastic into a moulding machine and it will create the part in cavities in the mould.
Injection moulding is the most common manufacturing process used to produce plastic parts. The process utilises an injection moulding machine, raw material, and a mould of the product part being produced to consistently manufacture high volumes of identical objects at a fast rate.
Another good thing about injection moulding is that it’s very versatile. You can use different kinds of materials for the injection molding process and there are many different types of plastics you can create parts out of.
If you want to make plastic furniture, the machine will melt down the plastic and inject it into a mould cavity. The machine will then rotate the part until it solidifies and cools before removing it from the machine.
You may wonder, how do they get that intricate shape? That’s where your mould comes in because it will give your product its shape. That’s also why having a good mould is so important when doing this process.
The raw materials used are chosen based on the function and specifications of the final product part. The material is melted down, and then fed into the injection moulding machine.
Injection moulding machines come in a variety of shapes and sizes depending on the number of parts being made and the space to be used by those parts. This can mean there are different sizes of injection moulding machines that are needed to process one type of product or shape.
These machines will often have an angled bottom where the raw materials float above a moving platform which drops them down into the machine. Depending on what type of material you choose, you will receive a certain amount of plastic each time it goes through the machine.
Step By Step Processes Involved During Injection Moulding
A typical injection moulding process usually involves several different steps, with each step involving a separate machine.
1. Prepare Your Materials
The first step in the process is to prepare your materials by mixing the plastic raw materials together and heating them to the right temperature depending on your application. You will then feed this material into a hopper located at the top of a machine that inputs it into a moulding machine.
2. Moulding Machine
This part of the process is where you turn your plastic material into a finished part that is ready for further processing. Injection moulding machines have different ways of melting down and spitting out molten plastic, with these processes varying from machine to machine.
After your part is formed, it will be injected out of the machine and moved onto a clamping machine. Here, the part will be held in place while it cools overnight to ensure that it is stable and has a strong structure.
The raw materials, usually in the form of pellets, are melted by heat and pressure, then injected into the mould very quickly, filling the entire space within it.
As the molten material cools, it goes through several stages of cooling. Depending on the type of plastic that is used, it will go through a process of gradual cooling in which the material will be cooled slowly.
6. Mould Removal and Cleaning
After a period of time, the mould will be removed from the machine ready for use in another process. The remains, also known as residue, is then cleaned up and filtered to remove any impurities that might remain.
This can take quite a long time depending on the size of your product and how dirty the residue is.
Moving on, now we know the processes involved in injection moulding, let’s go into the advantages and disadvantages of injection moulding.
Advantages And Disadvantages Of Injection Moulding
Here, we will be talk about the advantages and disadvantages of injection moulding but firstly, we will look into the advantages of injection moulding and then later its disadvantages.
Advantages Of injection Moulding
Some of the advantages of injection moulding are as follows:
1. High Efficiency In Production
Injection moulding machines are the most efficient way of making plastic parts. The reason for this is because by having one machine for every part, you can produce an unlimited number of products. This is due to the continuous production and the multiple injection moulding machines.
The plastic being injected into the mould creates many different shapes, which can then be pulled out as finished products. These products are made out of high quality raw materials and have a great finish that would not be possible without injection moulding machines.
2. High-Output Production
Injection moulding can produce a huge amount of parts per hour, depending on how many impressions are in tool, but you’re looking at something between 15-30 seconds for each cycle time.
The output of an injection machine is also very high. The machine will produce a large number of products every hour. The time taken to make a product depends on how fast the machine goes, how many parts are being made and the size of the parts being made.
3. Environmentally Friendly
The process of injection moulding is also very environmentally friendly because it uses recycled plastics that would have otherwise been thrown away. The materials are melted down, turned into a liquid and then replace into containers which can be reused many times over.
4. Low Labour Cost
Another great advantage of injection moulding is that it has very low labour costs. This is due to the fact that it does not require labour to load parts into a machine and place them in position within the machine.
This can be done by machines themselves, in which case the only person who needs to be inside is the operator, and then once again, depending on how complicated your parts are you can have machines that can do this themselves.
5. Design Flexibility
Another great advantage of the process of injection moulding is that it can make incredible designs because it is capable of producing any shape. This is due to the fact that when making parts, you will have many different types of moulds and molds to choose from.
The moulds themselves are subjected to extremely high pressure. As a result, the plastic within the moulds is pressed harder and allows for a large amount of detail to be imprinted onto the part and for complex or intricate shapes to be manufactured.
Disadvantages Of Injection Moulding
Some of the disadvantages of injection moulding are as follows:
1. High Initial Cost Of Machinery
The majority of the machinery used in injection moulding is expensive, due to its use of large quantities of materials and machine parts. The machinery can be costly, but it is a one time purchase and can be very useful in the long term.
The second most expensive part of injection moulding is the raw materials that are used, but more on that later. All in all, initial costs are always going to be high for an injection moulding company or plant because you’re paying for a lot of machinery and materials up front.
2. Part Design Restrictions
Another disadvantage of injection moulding is that all parts must be made within the shape of the mould. This means that there are very few limitations when it comes to designing your part, but it also means you cannot take on jobs with more complicated shapes.
As previously mentioned, there are many types of molds and mould types that can be used. Some are limited to three axis while others can go up to five axis and even beyond. The more complex the part, the further in price you have to go and it’s always going to be a compromise between cost and design if you have a restricted budget.
3. Difficult In Getting Accurate Costing
With injection moulding, you need to make sure you have an accurate costing department, which is necessary in order to know exactly how much money your product is going to cost when produced.
This can be hard because the production of plastic parts requires high accuracy and you are not likely to get any outside help.
This means it can be very easy for a company that does not have the experience or the equipment to produce parts at a similar level, to become overcharged for their product due to a lack of knowledge about how much those products are actually worth.
Uses Of Injection Moulding
Injection moulding is the preferred production method for most mass-produced plastic products, due to its high output rate and consistency of quality. Some of the uses of injection moulding are:
- Automotive parts – Because injection moulding is a very safe and reliable method of making parts, the automotive industry has become very popular in the plastic production field.
These are the sort of products that are made and sold around the world, including wheels, bumpers, windscreens, grilles, dashboards and seats. These are all parts that will be necessary to make a car function properly.
- Electronics – Injection moulding is one of the main ways in which electronics are manufactured nowadays, due to its unparalleled output rate of high-quality products and low running cost of production. Some of these includes: electrical connectors, enclosures, protective sleeving.
- Consumer plastics – The uses of injection moulding in the plastic production sphere are very wide, as it is most commonly used in the production of everyday plastic products such as: bottles caps, cups, containers, mobile phone cases, toys.
- Medical Devices – The medical industry uses injection moulding for its ability to produce high-quality materials with a large amount of detail and precision. These include prosthesis for severed limbs and limbs that are missing limbs.
Injection moulding is also used to produce medical implants and small surgical instruments, as well as other items relating to health care products such as sutures and needles. These includes: syringes, valves, dishes.
Injection moulding has some great advantages and disadvantages. However, it is still an effective method of producing parts, especially when you can get a good deal with the initial costs.
The biggest disadvantage of this process has to be the high initial costs needed to set up your production line as well as purchasing machinery and raw materials.
However, injection moulding is still a great way in which to make plastic products because of its versatility and efficiency in manufacturing anything from small plastic parts to large intricate objects.