Cheap injection molding is possible if you get it right. Make a simple part design, communicate with your injection molder, and compare advantages of offshore and onshore. You will save your money for your project.

To some customers, this could be difficult to decide. They would say: “well, I don’t know. It’s a new product, let the market decides” or “just give me the price, you don’t have to worry about the quantities”. Actually, an unsure mold life will surely make the injection molding not cost-effective. Why? The mold maker will have to use a longer mold life in case you need an increasing volume in future. So no mold life equals to longer mold life to injection molding manufacturers.

Black is a popular color, which applies to a wide arrange of  plastic housings. If white or clear colors required, the injection molding manufacturers will have to use many resins to clean their machines first to avoid leftover colors. Also, a cleaner injection condition is required to avoid black spots. So if you want cheap injection molding, sometimes you would have to give up using white or clear colors.

One of the most common defects in Injection Molding is the short shot.  I remember many times that I was called to a machine to diagnose a short shot in the production run.  At the time I worked in high cavitation thin-walled molding and short shots and flash were the 2 critical defects we had to really keep an eye out for in that production environment.

Cheap injection molding is essential especially when you have a limited budget for a new project, or just need a low volume of injection molding production. There is another reason why you need low-cost injection molding: your volume is high, but the end users need affordable plastic parts, like dispensable razors, plastic caps for toilet cleaners.

Short shots or “shorts” are the incomplete filling of a mold cavity.  Some shorts can be easily seen as a large part of the cavity missing and some are very small and hard to see with a visual inspection.  Several factors can lead to short shots.

Also, keep the less molding processes as less as possible. Co-molding or overmolding seems great for bonding 2 plastic part together, but it is expensive as well. There’s solution like to make 2 separate parts, not via co-molding to save the injection molding cost. For overmolding, you may consider tapping the plastic parts manually by end users. This is often seen like fan shrouds of a battery or electronics housings.

With labor advantages, offshore injection molding like China is mostly competitive on pricing. However, you may compare China pricing with onshore’s, especially for a small run of 25 or 50 pieces. In this case, China injection molding may not be cheap, as local companies could use Aluminum molds Also, consideration on international shipping cost and lead time are also necessary.

Whether your volume is 100,000 units or 100 units to start, in today’s post, I’ll share 6 practical tips you can use to get your own cheap injection molding.

The more complicated you parts are, the more money you would spend. Keep the part design simple is the most important factor for cheap injection molding. Undercuts on the parts add both tooling and molding production cost. Most of the undercuts could be avoidable if you redesign your part.

When a manufacturing facility comes bigger, so does their profit, as they will have to pay off the factory rent, human expenses, and managing cost to maintain their running. However, these will make your injection molding expensive. So if you work with a small injection molding company, everything is based on lower pricing.

Purging Compounds are an easy-to-use and affordable way to dramatically reduce scrap & downtime in plastics manufacturing. But how do you know if purging compounds are right for you?

Asaclean® helps injection molders, extruders, and blow molders dramatically reduce scrap and downtime. Whether you’re struggling with hot runner color changeovers, costly screw pulls, or holding a bubble in blown-film extrusion, we have the solution to your problems.

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Jeremy Cooley is an Asaclean Technical Service Representative & Purging Expert living in South Carolina. He's worked in injection molding & purging for over 15 years, and frequently presents at national plastics trade shows and conferences.

A) use a Multi-cavity molding solution if you have many parts. This will lower the setup tooling cost much. B) use a non-prehard mold steel like 738H. C) use existing mold base they have to save more mold cost. D) make a simple mold design like manual molding solution, not automatic.

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Many times shorts are related to a faulty process.  Inadequate injection pressure or injection speeds can cause shorts.  If the screw is bottoming out at the end of the cycle resulting in a zero cushion then the process can’t be relied upon as repeatable and many times this can generate shorts.  If shorts are present in the production run the process should be checked as well as the resin being processed as a change in viscosity can throw off the process and cause defects in the production run.

The venting of the mold can also contribute to short shots.  If the mold is not vented properly it is possible for the gas to not be able to escape the cavity in time for the molding cycle to complete.  This can result in a short shot since the material can’t fill the void in the cavity because the gas hasn’t vented.  The vents on the mold should be checked for blockages and repaired if needed.

In other cases, the customers brief the molders the mold life clearly, like 1,000 pcs per order. 50,000 pcs for mold life. This will send them a message: the project is for the low volume of injection molding, and it should be as cheaper as possible. In China, mold makers might consider making the mold as below to lower the mold cost:

The process of injection molding may not cheaper than you thought. For some parts, use other processes like 3D printing, CNC machining, blow molding or plastic extrusion could be more cost-effective. To give you an example, the below part design is much cheaper than injection molding: extrusion mold cost of US$1000, comparing injection mold cost US$3500.

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