Expert Advice on How to Reduce Plastic Injection Molding Costs 
Choose the best material – and best does not mean most expensive
In a previous article “Plastic Injection Molding – Choosing the right kind of resin” we looked at the importance of identifying the best materials in detail, but now we’ll look at cost v.s. quality. There are literally hundreds of plastics that can be injected into a mold, but the key points you need to consider when considering your projects are:
- The required strength application of the part, does it need to be flexible or rigid?
- The final finish of the part, what appearance it will have including surface texture and transparency and color requirements?
- Regulatory requirements for the region you are producing for, i.e. EU regulations differ from U.S. regulations, does it have to be RoHS, REACH, EN 1452 or FDA compliant? Does it need to be food grade and BPA free?
- What chemical or environmental elements will the part be exposed to, i.e. rain, the wind, snow, the sun? Plastics primer – Thermoset v.s. Thermoplastic
- What is the life expectancy of the part?
It’s important to remember that the most expensive, best-rated, state of the art raw materials aren’t necessarily the best for your project. It might be rated as the “best” but if its properties aren’t suited to your products it might just end up costing you more but without any added value. Why opt for a 40% glass filled nylon when polyethylene would work just as well without the price tag?
Choose a good-fit company to produce your products
There are thousands of injection molding companies to choose from ranging from small, mid-sized to very large. One company might be better suited to your needs than others. Smaller companies can be more flexible with MOQ’s and the service can be more responsive than large companies but it’s not a set rule. It’s sometimes easier to negotiate with small to medium sized companies on price but large companies buy raw materials in bulk which comes with a reduced price tag
A good rule of thumb is to choose a molding company that has experience producing your type of products. Bigger doesn’t necessarily mean better quality, look for a factory that puts quality and excellence as their main priority. Do they have a section dedicated solely to quality control, how often are parts inspected during production, is the company running lean by implementing six sigma strategies? Provident works with a single American-owned molding and mold-producing company that goes above and beyond to provide quality products.
Consolidate your Processes
Molding is the first step in a series of processes when you’re creating products from the ground up. Examples of these processes include – labelling, custom inserts, assembly, painting, packaging, etc. All these take time and are usually very time-consuming because they require extensive setups to run efficiently. The entire reason you’re using injection molding is that it’s a fast process, but if you don’t manage the other processes equally fast it’ll end up wasting a lot of time and money.
How do you avoid expensive or delayed processes?
Combine everything into a single robust process. Find, or switch, to a manufacturer that can manage as many of these processes for you in-house. Why Provident works with a single-source manufacturer is because everything from engineering/manufacturing the molds to labelling and packaging products happens in-house. It’s not always required, but depending on your products it’s a good option to have and it cuts a lot of costs if you can consolidate processes. Work only with companies that have a proven track record that design products with defect prevention in mind.
It’s no secret that buying in bulk is less expensive than purchasing small quantities. Most molding operations aim to produce in large volumes, and the goal is to produce as much as possible as quickly as possible. Many companies produce thousands of prototypes in the research and development phase alone, to take advantage of extensive testing and feedback. As soon as the products move into the production phase it’s crucial that you’re able to produce as many parts in one shot as possible.
Molds used for production should have as many cavities as possible without making concessions on the quality of the parts produced. In a very competitive marketplace today, products need to be the best they can possibly be, and quality is key. Produce as many parts as possible at one time, this will spread setup costs out over more parts which will lower the price per piece and cut costs, making you more competitive in the marketplace.
Make your molds cost-effective for injection molding
Wait what? As previously mentioned, in bulk production it’s beneficial to produce as many parts as possible in one go. However, it’s equally important to eject the plastic product quickly and prime for the next shot without wasting movement. Fluid is fast, and fast is good! Parts are typically ejected with air blasts, rods or a plate.
Every second counts towards the overall cost of your products, and in this case, time really is money. It’s essential to reduce the mechanisms of molding to be as few and fast as possible, which starts with your mold design. Work with engineers that understand the need for optimized mold designs.
Develop product designs for optimal material use
You can cut material consumption considerably (and cost) with optimized product designs. If a product has a mechanism (like a hinge) it can be incorporated into the molding process, taking away the need for secondary processes or machining. Living hinges, typically found on shampoo bottles, can be produced by making use of the properties of the material that is used to mold the plastic part.
Utilizing gussets and ribs to reinforce a product will save on material consumption, as well as the added benefit of a uniform wall thickness that’s neither too thick or thin. The mold needs to have enough draft to allow quick product ejection from the mold to improve the speed which saves time and in turn money. In the end, you don’t need to reinvent the wheel. If you’re looking to cut costs, switch manufacturers, or develop new products there are experts that can assist you with design, planning and execution to run your projects cost-effectively. View our partner’s website and see what is possible