Extrusion and injection molding are almost the same in manufacturing. They use melting material to produce prototypes of different parts of the machines, and they can produce higher quantities at a lower cost without pausing after making each prototype.
Despite all these similarities, you can still consider them the same procedures. Yes, they both give prototypes, but they have their differences.
These differences change the applications of extrusion and injection molding. Extrusion is mostly used for two-dimensional products, while injection molding is suitable for three-dimensional products.
Do you know?
According to a report, the market price of injection-molded plastics globally in 2020 was $343.23 billion, and this market value is estimated to increase to $476.46 billion in 2028. Yes, this is huge, but that explains how much these molding procedures are making their place worldwide.
So let’s look at the extrusion vs. injection molding for a better insight.
The Key Differences
| Extrusion Molding | Injection Molding |
| Good for two-dimensional products. | Good for three-dimensional products. |
| It cannot get into more details and makes linear rod-like molds. Yet, it gives an inner detail to these rods forming different designs. | Create complex prototypes with more details, giving the real product’s exact look. |
| A cost-effective procedure as compared to injection molding. | Expensive production, yet the cheapest one in terms of three-dimensional products. Other procedures, like CNC machining, are more expensive. |
| Produces long rods of 1000 ft or above. These rods later need to be cut with band saws. | Hundreds of products that can be manufactured at a time without a break. The same molds are used repeatedly, saving time and cost. |
| Extrusion can work with less fluid materials. It has a high melting strength during the procedure. | It demands more fluidity of the material for making high-quality molds. |
The Injection Molding Process
Injection molding is the most cost-effective way when you need plastic products at scale. The process of injection molding starts with a plastic resin; this plastic resin is melted into molten material and injected into the mold tool.
Once the melted resin solidifies after cooling, it is removed from the mold. The result is a three-dimensional shaped product with an extremely smooth surface finish.
The best part about this process?
It can be repeated hundreds of times without increasing costs and other factors.
Injection Molding Applications
Suppose you are curious if injection molding suits your industry. Here are some of the industries that use injection molding for manufacturing different parts and products.
Automotive
Under the hood components, fenders, bumpers, door panels, light housing, and many other parts of the vehicles are designed with injection molding. It provides more effective and cost-saving for making these parts.
Pharmaceutical/Medical
From medical devices to inducing controlled doses of medicines, injection molding is used everywhere in the medical industry.
Being a cost-effective and highly precise procedure, it is preferred for making medical equipment parts. Every part made with injection molding saves a person’s life. That’s why it requires high precision.
Aerospace and Defense
Multiple custom plastic aerospace prototypes are produced using injection molding. The reason is their light weightlessness and durability, which are highly required in aerospace. Turbine blades, window bezels, battery housing, and pilot tubes are common products designed with injection molding.
Construction
Throughout the construction industry, injection molding is a very important procedure. Many products made with injection molding are used in construction, and flooring, windows, walls, and piping all include injection molded parts.
The Extrusion Molding Process
When continuous linear bars are required, extrusion molding is the best procedure. An extrusion machine is used in the process of extrusion molding. The molten material is passed through this machine that comes out from the other end giving two-dimensional rod-like shapes.
The resulting product is a complex cross-sectional structure having a particular outer shape.
These rod-like structures are usually 100 to 1000 feet long. Once they are produced, they are cut through using a band saw. Cutting pieces depend on the required length by the manufacturer.
Extrusion Molding Applications
The applications of extrusion molding are also expanded to many industries. With it, lots of procedures and processes might be possible today. So here are some of its applications for you to understand its vastness.
Automotive
The use of extrusion molding is extensive in the automotive industry because of its ability to produce cost-effective parts.
One example is aluminum extruders in the automotive industry, which explains how multiple products from extrusion molding are being used in the automotive industry today.
Aerospace
Aerospace industries require highly complex nature parts. The extrusion parts are used in the aerospace industry for seat tracks, lower wing stringers, floor beams, and even fuselage stringers. Without extrusion molding, designing a full aircraft is not possible.
Construction
The construction industry is where extrusion molding is mostly used. When constructing any building, many pipes, rods, and other relatable things are involved. That’s what extrusion molding is known for.
Sheets, pipes, wire coverings, and more are made with extrusion molding for the construction industry.
When to Use Extrusion and Injection Molding
If you need clarification on extrusion and injection molding, you must know when to use which. Check out some of the points of using each process. It will help you make a better decision.
Extrusion Molding is Best Suited for:
It is best suited for making continuous linear bars with advanced cross-sections. They can also have inner voids and external shapes depending on the requirement. These long roads can be between 100 to 2,000 ft long and are cut with a band saw in the desired length.
From the point of view of people, extrusion molding is more popular, and it is involved in plastic tubing and even different pipe products. Plastic coatings, insulation of wires, and even plastic films can use an extrusion process for better results.
Injection Molding is Best Suited for:
When there is a need for manufacturing more than 1000 parts in a single batch, then injection molding is best. These parts can be of different sizes and complexities, lowering costs. The injection molding process depends on a mold tool to exactly the product’s shape.
This procedure can be repeated many times, decreasing the cost of products with every batch. Where cost is a greater factor, injection molding would be good.
Injection Molding vs. Extrusion Molding: Pros & Cons
Every procedure has its ups and downs. Knowing the benefits and drawbacks of a procedure would make it easier to choose anyone. Check out the pros and cons of extrusion versus injection molding to clarify your doubts.
Injection Molding Pros
Injection molding can be the quality of a CNC or 3D printed product; first, it offers better precision and decreases any need for post-processes. The best part is its repeatability, which reduces the cost and time spent manufacturing multiple products.
Do you want to know more about the pros of injection molding? Here they are.
1. Precision
The average tolerance of any injection molded product is +/- 0.005 inches. That’s the highest count of precision that you can achieve by any procedure, and you have high precision with injection molding.
2. Compatibility
Injection molding is universally compatible with almost all types of plastics. You can choose any plastic type that coincides with your purpose. The compatibility offered by injection molding helps with better versatility for any product development.
3. Consistency
Consistency refers to the exactness of all the products manufactured with injection molding. No matter the batch’s size, you will see the same consistency without flaws. Even if there are hundreds or thousands of products, the geometric properties will not change.
4. Productivity
Multiple parts are controlled in one cycle, which means there is a better chance of effectiveness and efficiency of production.
The enhancement in productivity is also related to no post-processing required. When these products come out of the molds, they’re ready for selling in the market.
5. Surface Texture
The products manufactured with injection molding have a surface texture, which is supposed to improve the overall look and functionality of the product.
High-quality molds provide a better surface texture, increasing the functionality and aesthetic look of the product.
6. Repetition of Molds
Once the molds are used, they can be further utilized for making similar products. However, if there is no need for further similar products, these molds can be reshaped, saving the overall cost.
Injection Molding Cons
Remember to look out for the cons of injection molding, as they might not please you.
1. Higher Costs
Setting up an injection molding process involves many costs. Everything is expensive and cannot be skipped, from the machine to the molds. When dealing with small to medium manufacturing units, cost becomes a bigger concern with injection molding.
2. Longer Lead Time
For every product manufactured with injection molding, there’s a need for specific molds. Even with starting the exact process, a lot of time is taken to make molds.
It means longer initial times for starting the procedure are involved, negatively impacting performance.
3. Not For Lower Volume Production
Injection molding is designed to produce hundreds and thousands of products simultaneously. Yet when there is a lesser volume, production required using injection molding isn’t wise. It can cost a lot compared to other molding processes.
Extrusion Molding Pros
Extrusion is used in metals and plastics, but plastic extrusion has different pros. Check out the following good points about extrusion molding for plastics.
1. Cheaper
The overall cost of plastic extrusion is less than injection molding, and it is one of the best benefits as everyone looks for cheaper solutions.
Noncomplexes and 2D parts are better for manufacturing with extrusion. Even with lower cost, you get high quality and quick results within a short time.
2. Good Surface Finish
In the extrusion process, plastic is forced out from a small opening. This reduces the chances of air bubbles or other flaws in the final product. It means there is a high-quality surface finish with less post-processing required.
3. More Productive
For high-volume production choosing extrusion molding is a good idea. Many parts can be made at a time, saving time and cost. However, you can attain a different level of economy with extrusion.
4. Versatile
No matter how complex two-dimensional designs you want, extrusion molding can easily help you through it. Numerous types of plastics are easily handled with extrusion molding. You don’t need to look out for other procedures when dealing with versatility in molding.
Extrusion Molding Cons
When dealing with basic plastic parts production, you can dress extrusion. However, there are disadvantages associated with it.
1. Deviations in Size
In case of any deviations in the size or the cross-section, it would be difficult for extrusion to handle. You will need a different dye, even if you need a minor change. It eventually increases the time of production and sometimes even costs.
2. Cost
The overall setup cost of extrusion molding is particularly high. Although the cost of extrusion tools is cheaper, it increases compared to the total cost. It means if you are looking for extrusion molding, you must pay more for your molded parts.
3. Environmental Effect
The negative environmental effects are the biggest drawback of extrusion molding. No doubt, the environmental effects are also involved in injection molding.
However, the products or parts made with extrusion could be stronger. It means these products cannot be reused. It ultimately impacts the environmental cost in contrast to injection molding.
Extrusion Molding vs. Injection Molding Cost
The cost of injection and extrusion products are both low compared to the other procedures in the market. However, if we are to compare prices between these two procedures, there are some factors.