5 Essentials for Your Best Plastic Injection Molding Quote



You have a project that requires plastic parts. You did your homework and found a reputable shop to help you determine the feasibility of using custom injection molding to produce the parts. Now you’ll need to give the injection molding shop some specific information to ensure that you’ll be getting exactly what you want.

While there might be (and probably will be) additional information that you’ll be asked to provide throughout the project, here are the five essential items that the plastic injection mold shop will need from you so they can give you an accurate quote:

1.   A CAD drawing or a sample part

Everyone should be familiar with that old idiom “The devil is in the details.” Well, the details, as they pertain to your part, must be properly communicated, or you could end up disappointed in the results. Hand-drawn prints are somewhat a relic from the past.  They might still work to get a ballpark estimate, but need to be CAD files for detailed quoting purposes. CAD drawings are required for translating dimensions for the mold design and the manufacturing of the mold.  With today’s technology, sample parts can be scanned to provide an accurate 3D CAD model. Unless you are supplying your own mold, your injection mold shop will be depending on you for the details of your part.

2.   How the part will be used

The injection molding company that’s quoting your part needs to understand how it’s going to be used. Why? Knowing the application will help them to make recommendations on the material and the color to be used and perhaps even give you some design suggestions. Here are some questions that you should answer before requesting a quote:

·         Will the parts be used outside?

·         How much impact will they sustain?

·         Will there be excessive wear and tear on the parts?

When you give the mold shop this application information up front, you help to eliminate unpleasant surprises somewhere down the road.

3.   The type of material and Color

To the uninitiated, plastic is plastic. But you probably already know there are tens of thousands of grades of plastic from which to choose. These available varieties come with a wide range of prices. So, you can end up paying a lower price per pound for commonly used grades and a much higher price per pound for the highly engineered variety.

It’s easy to see that assuming the wrong grade of plastic will scuttle the chance for an accurate plastic injection molding estimate. If you’re not sure, discuss things with the mold shop. They can make suggestions that will keep you from over-engineering and wasting money.

4.   How many parts you’ll be producing

You should be able to estimate how many parts you’ll need each year. When the tool and die shop quotes your mold, two factors will have a significant impact on the price: What material will be used to manufacture the mold, and how many cavities will be built into the mold. If your annual quantities are high, your injection mold tooling costs will be higher since more cavities and hardened tool steel molds will cost more. But your price per piece will be lower because of the extra cavities, and your tool steel mold will have a much longer life.

5.   A list of secondary operations, if any

You should inform your chosen mold shop of any secondary operations that will be required. Depending on what those operations entail, the shop may be able to complete them and save you the expense and inconvenience of going elsewhere for them. Assembly and packaging are examples of secondary operations that many shops would be willing to take on. Again, you could lower your per-piece cost with what you save on handling costs alone. Be sure to include these secondary operations on your request for quote.


Planning for plastic injection molding can be confusing for even experienced manufacturers. Let us help you through the process by clearing up some of the confusion. Call SEA-LECT Plastics @ (425) 339-0288 or email mattp@sealectplastics.com for consultation.