Calculating Injection Molding Costs: Tips and Facts You Need to Know

Injection molding is one of the most popular manufacturing processes alongside CNC machining and 3D printing. However, it is notorious for its relatively high prices unlike the other two. Many factors, such as the complexity of your product, the quantity of the product, etc., go into determining the price of an injection molding process.

This article will explain why the process is expensive, how machinists calculate and even suggest useful tips on how to reduce your injection molding costs.

Why is Injection Molding So Expensive? 

Plastic injection molding produces plastic parts by heating plastic particles to their melting points and injecting them into a metal mold. The process involves leaving the molten plastic to cool and retain the shape of the mold when it hardens.

The injection mold used to shape the molten plastic is unarguably the most expensive part of the molding project. But why is the mold expensive? Here are some reasons below.

1. The materials used to make the mold are quite costly

The materials used for making the mold have to be high grade, hence their expensive cost. This is because plastic injection molding requires thousands of pounds of pressure to make plastic pellets, and a weak mold cannot withstand such pressure. Thus, machinists make the mold out of solid materials that can stand the test of time and not deform in the face of such high pressure. 

The mold base contributes to the high cost of injection molding.

The mold is like a case holding all the mold cavities in place. It also holds the inserts and other components of the mold together. The bigger the size of the mold, the costlier the base.

2. The complexity of the part to be produced

The complexity of the part you want to produce is another factor that determines injection molding costs. If you want to make complex parts, you have to spend more to design and machine a complex injection mold. In other words, the more the complexity of the parts you want to produce, the more complex and costly the mold.

Once they make a mold for a particular design, modifying it is sometimes impossible. Hence, if you need to make multiple designs, you may have to purchase new molds. This is another reason why molding is so expensive.

Breakdown of Injection Molding Costs

To make an accurate calculation of the cost per part of injection molding, we need to factor in all the manufacturing processes and what those processes entail. These factors include the cost of labor, type of materials used, etc. In this section, you’ll learn how to calculate plastic injection molding costs.

1. Cost of the plastic injection mold

As earlier discussed, injection molds come in different sizes and sell at different prices. To purchase a plastic injection mold, you may be looking at spending a thousand dollars or even tens of thousands, depending on the machine’s complexity. However, if you need a single cavity mold, you don’t have to bother about spending so much on purchasing a mold with multiple cavities.

2. Cost of polymer resin material

Polymer resin is an essential part of production. Therefore, the quality of polymer resin used in the production will influence the plastic injection molding cost. For instance, if you make parts using engineering resin with extra strength and chemical resistance, the material will be a little more expensive than those made of commodity resin-like polyethylene. If you want low-cost injection molding, you can opt for plastic resins made from recycled plastics. They are more affordable.

3. Cost of labor

Although the company is fully in charge of hiring the machinists needed and maintaining of machines and tool bits needed for the job, the cost of labor will be partly included in the quotation you receive, which is also a part of the custom injection molding cost.

Tips to Reduce Injection Molding Costs

Saving costs on manufactured parts is not rocket science. Therefore, you can reduce your injection molding costs without compromising the quality of your produce. The following tips will save you some dollars while working on your molding designs:

1. Avoid unnecessary features

In most cases, molded part numbers, textured surfaces, and company logos are unnecessary for your designs. They consume extra polymer resin, which will add up to your injection molding costs. However, in some cases like military applications and aerospace, permanent part numbers may be required and cannot be omitted.

There are still ways around that. You can still save costs by using a mill-friendly font like Arial, Century Gothic Bold, or Verdana (san-serif fonts). To further save cost, you need to do more than opt for these fonts.

It’s not advisable to go deeper than 0.010 or 0.015-inch maximum. Going deeper will require more resin, and that is not economical. You should keep your font above 20 pt so that they are legible enough to read. You could use our injection molding design guide to check if your design is a good fit for production.

2. Only use cosmetics when required

Putting beautiful surface finishing on your plastic molded parts is nice, but some cosmetics should be avoided to save cost. You’ll spend some extra dollars by using EDM, bead blasting, high mold polish, etc., for your design, whereas, in some cases, they are not essential. If they are not needed, you should avoid using them to save costs. However, if you must polish the parts, you can still save costs by polishing half of the mold or the small area needed instead of polishing the entire part.

3. Mold mods

You can re-machine an existing mold to suit your new need instead of purchasing a new one. This process might be complicated, though, but if well done, it’ll save you some dollars. Purchase the needed parts, and replace the old parts with them. That way, you’ve upgraded your machine to meet your new need without purchasing a new one.

4. Choose a suitable mold size

You can save yourself unnecessary stress and injection mold cost by purchasing a suitable mold size for your parts. Size in this regard refers to how big the pieces you want to design are and the volumes required. Some injection molds are ideal for smaller part quantities, while some are designed for larger quantities. To manage the demand volatility of your parts and leverage cost-efficient bridge tooling, you should choose a suitable mold size.

You could also use our instant quoting platform on RapidDirect, which gives you an estimate for the cost of your injection molding process within a minute. It calculates this using all the factors that we’ve mentioned earlier and gives an accurate result.

Custom Injection Molding Services With Competitive Pricing

Have you been searching online to find a suitable firm offering quality custom injection molded prototypes and production parts? Then, you just found what you are looking for. RapidDirect is an expert in the injection molding services.

You can rely on us to get prototype molds durable with up to 10,000 components. One incredible feature that stands us out from others is our ability to provide you with an accurate quote in less than 24-hours. We know how much you value time; thus, we are time cautious. More so, we’ll provide you with in-time progress feedback and coordination during production. Therefore, you’ll not be kept in the dark during production; instead, you’ll see how committed we are to your project.

Do we have the robust capabilities required for your large project? Yes! We have a vast in-house factory denoting our supreme manufacturing capabilities. Therefore, you can rely on us to deliver your injection molded prototype parts on time.

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Conclusion

Injection molding is a popular manufacturing process due to its cost-effective solution to scale and produce a large number of parts. However, it could be quite costly, especially when you’re only making a handful of parts. You can read up on this article to find useful tips to reduce your injection molding costs or use our instant quoting platform to get an estimate for your injection molding process.