Injection Moulding Specialists

Our Layman's Guide To...

Plastic Injection Moulded Parts

If you've never bought plastic moulded parts before, hopefully this guide
will explain the basics and give you an idea of the costs involved.

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Plastic Part Design

You need to start with the basic plastic part design and we are happy to do this for you FREE OF CHARGE, working from a brief description, sketch, drawings or CAD data. We will also need to know the part's end use in order to select the right plastic material for the job.

Once we have the part fully designed, if deemed necessary, we can produce a 3D printed model for you to assess and make any minor alterations if needed. Once you are happy with the design, we can then provide you with a firm quotation for the mould tool and moulded parts.

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Mould Tools

Also referred to as Mould, Tool, Tooling. Unfortunately, it has to be designed and built before you see your first moulded part. Delivery time can be anything from a few weeks to several months depending on size and complexity. Mould Tools are precision, highly engineered equipment that take a lot of man and machine hours to produce. They are subjected to enormous pressures every cycle when running.

In real terms, tooling costs have reduced over the years due to the advent of Computer Aided Design & Manufacturing (CAD/CAM). As a very rough guide, a Tool to produce a simple 50mm box would cost you a few thousand pounds. A mould tool to produce something like a car bumper and you can be looking at 6 figure sums! The tool has to be paid for by you in stages of build and is your property, but it is normally left with your moulder who runs it whenever you require parts.

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Mould Tool and Parts Produced

Mould Tools can be made from various materials depending on the life required, i.e., if you know the requirement is for millions of parts, then the tooling would normally be manufactured from Hardened Tool Steel. For a few hundred thousand parts, a pre-toughed steel is normally adequate and has the advantage of being easier to machine and costs less. For lower quantities still, Aluminium is an option and results in even lower tooling costs and faster lead times.

Instead of the Tool only having one cavity, it could have 2 (or more). The downside is that the tool costs more, but not twice the price. Upside is that 2 or more products are produced in the same amount of time as it takes to make 1 part from a 1 cavity tool, resulting in a lower part cost.

By now, you are probably realising that the decision on the tool material type and the number of cavities depends on the number of parts you think will be required over a products lifetime, never easy, but we can advise your best options using our specialist costing software.

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Plastic Raw Materials

Show a Layman a plastic part and ask them what it's made of! "PLASTIC", is the inevitable answer!

There are many different types of plastics (thermoplastics to be precise), a lot of them you will have heard of like Nylon, PVC, Polystyrene, Polythene etc. In the moulder's world there are many more. Each type also has variants and the type is selected depending on the properties required for the finished parts. The materials can be filled with things like glass fibres or spheres, talc and other stuff, which enhances certain properties of the base materials such as strength, rigidity, flexibility or heat resistance.

Prices vary enormously depending on type, grade and colour, but to give you and idea, if the material cost is £2.00 per Kilo and your part weight is 10 grams, then the cost of the material content of your part will be 2 pence.

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Moulding

OK, we've got your Mould Tool and Raw Material, now we've got to make your MOULDED PARTS.

We put your tool into one of our Injection Moulding Machines, fill the hopper with raw material and press the start button. (if only it were so simple)! The cycle time of the machine is determined by the part design. Thin part sections cool faster than thick and therefore can be cycled faster. As a rough guide, a part with a 1mm wall section might cycle at about 10 seconds and 3mm at around 30 seconds.

So, how much does this bit of the moulded part cost? Most moulders will have an hourly rate based on the size of the moulding machine been utilised for your job, so if running a 2 cavity tool at 20 seconds (360 parts per hour), the part cost is Hourly Rate/360.

There may be after operations such as assembly or printing and these costs are calculated separately and added to the piece price.

There will also be packaging and delivery costs and of course, big parts use more packaging and usually cost more to transport.

We hope this simple guide has helped explain the process and costing. In reality, every job is different, but with our experience we can make everything easy for you. Once you've instructed us to proceed, all you have to do is relax and concentrate on the stuff you're good at.

Contact us...

Dickinson Philips Ltd, Snaygill Industrial Estate, Skipton, North Yorkshire BD23 2QR

Tel: 01756 700 359 Fax: 01756 700 360

[email protected]