Injection moulding is a manufacturing process used universally to manufacture various everyday goods. The majority of mass-produced products contain plastic injection moulded components including furniture fixings, plastic cutlery, CCTV cameras, games consoles, toasters and vacuum cleaners.
Top Tip: Click here to read our detailed guide on injection moulding to find out what plastics can be used for injection moulding.
What are the benefits of injection moulding?
Injection moulding can be a time-effective, cost-effective solution to your manufacturing needs as you can mass produce parts to a high quality. Through careful planning and adaptation throughout the injection moulding process, you can reduce the plastic injection moulding cost without sacrificing on quality, consistency or lead time.
How much does plastic injection moulding cost?
The price of injection moulding varies with every project. Due to the initial upfront cost of the mould and tooling, the greater the number of parts being produced, the lower the overall unit costs. This is because tooling costs can be absorbed across more parts. Mass-produced parts often use injection moulding as it is the most economical and timely way to produce plastic parts at high volumes.
Set up costs of injection moulding
The initial costs of setting up injection moulding are usually more expensive, as this will include the design and consultation process as well as making the mould. This is why many companies that use injection moulding will mass-produce products, as over time this will reduce the overall unit costs.
For example, the tooling costs for an injection moulding project can be several thousand of pounds (depending on complexity). Part costs, on the other hand, are in the region of a few pennies to a few pounds, depending on size and complexity.
Ways to reduce costs in injection moulding
There are several main cost drivers with injection moulding projects. Consequently, there are methods and best practices you can apply to reduce the costs of injection moulding for a more cost-effective solution whilst still providing excellent results.
Larger production runs can be beneficial in that they can benefit from economies of scale which reduce unit costs. However, depending on budgets and requirements, larger production runs may not be suitable as they often result in surplus stock and waste. If you are looking for further ways to reduce costs in your injection moulding project, this guide analyses injection moulding costs and offers solutions and ways to save money throughout the injection moulding process.
Injection moulding machine costs are determined by various factors, including:
- Material type
- Part size
- Complexity of design
- Cycle time
- Surface finishes and tolerances of the finished product
- Shipping and logistics
Below are some of the easiest ways to reduce costs in injection moulding.
Consider the materials you use
The materials used in injection moulding can play a large part in determining the final cost. Therefore be sure to look into your options, to make sure you’re choosing the right material for your finished product. Depending on the plastic thickness, weight and quality, and the desired requirements for your final product, you can save considerable money. The cheapest injection moulding plastics include ABS (acrylonitrile butadiene styrene), PP (polypropylene) and HIPS (high impact polystyrene). It also worth considering using recycled material, if the product does not require virgin material it could offer a cost-saving and win for sustainability.
You can read our design guide on injection moulding to learn about the types of plastics that can be used in injection moulding.
Do also consider the material the metal mould is produced from. Quality moulds cost more money, however, with this additional cost, comes a greater likelihood that the design process will run smoothly for many years with the best possible results.
It’s important to remember that cheap moulds will require maintenance, and may wear faster depending on the machining process and complexity of the final design. It is important to estimate the expected lifespan of the tool and match this to the expected demand forecast of your plastic parts.
Designers will need to balance material, cycle time and labour when finalising a cost for your injection moulding needs. Cycle time can be reduced in a number of ways. Widely speaking, some plastics are easier to mould than others and thinner features will have a faster cooling rate. These factors can drive down costs. It is best to experiment with different materials if you are unsure, before finding one that gives you the quality finish you want, at a cost you can work with.
Invest in people, not machinery
Although large parts of the injection moulding process are machine-driven, there are additional labour costs to oversee and execute the injection moulding process. This includes developing and designing the mould and overseeing the manufacturing process. Being experienced with the machine, and being able to identify and adjust certain variables as and when needed (injection speed, holding time, etc.) will minimise the risk of human error, meaning your final product will be of a high-quality finish. Choosing the right company and people to partner with will ultimately reduce reject rates and associated costs further down the line.
Labour costs, capacity and skill can fluctuate and vary across the globe and there are certainly opportunities to reduce costs by looking internationally. A common option is to manufacture the tooling internationally in a country like China and then mould the parts locally in the domestic market, cutting down on transport costs and lead times, making both the tooling and delivered part costs attractive. Although do bear in mind that communication can be hampered by using international suppliers. An alternative is to use a Manufacturing as a Service provider such as Get It Made who can harness international prices whilst still providing excellent UK based customer service.
Optimise your product design
The mould design and product design are also vital areas in which the costs of injection moulding can be reduced. Every injection moulding tool is custom made, so there are opportunities to reduce the cost and initial lead time when developing the mould.
By optimising the product design, you can ensure all-around efficiency, for example, part size, wall thickness, undercuts. Generally speaking, the larger the part, the higher the cost. Smaller parts will naturally take less time to cool which reduces the overall cycle time. A faster cycle time results in lower overhead costs, as well as labour costs.
Ways to optimise your injection mould design
Undercuts require more complex tooling such as sliding cores. Eliminating undercuts can lower tooling costs and avoids additional time being spent working on the mould. For example, the clip feature on the left below is complex to injection mould due to the undercut present. By adding a slot underneath the clip feature, the undercut is removed and the part can be tooled far more easily.
Remove unnecessary features
Features such as moulded part numbers and company logos are ‘nice to have' but can be costly additions. If you are looking to save money, a simpler design that removes these features is certainly a way to do it. Using a mill-friendly font as opposed to a more complex, difficult to machine font is another simple way to reduce costs.
Avoid cosmetic finishes
Again, although cosmetic finishes can be a good addition to the final product, improving quality. Elevated cosmetic touches and textured surfaces drive up tooling costs and may require additional elements such as bead blasting, photo etching textures or a mirror polish.
Consider mould thickness & quality
In order to ensure the mould cools at a sufficient rate, make sure that the mould is insulated from hot runners, and reduce the mould thickness wherever possible, too. A knowledgeable injection moulding company will be able to design an optimized mould design based on your parts and requirements.
Material and colour
The type of plastic used in the injection moulding process can make a huge difference to the final costs. Furthermore, additives (such as flame retardants and plasticisers) and colour pigments increase the cost. The more demanding the product requirements, the greater the material costs.
Smart injection moulding machines and technology allow for automation that ensures the moulding process is streamlined. Automation can also reduce lead times by allowing for 24-hour continuous production. Automation can offer additional savings as it reduces ongoing labour costs. Human error is also significantly reduced with the use of automation reducing costs arising from quality issues.