Aug 03, 2015

engineering drawing

We get a lot of inquiries from individuals and companies that are in the beginning phases of developing a new product. Others have already made their product, perhaps domestically, and are asking us to quote it from China.

If the product is something simple like a basketball, belt, apparel, or perhaps a simple office product, or if it’s an item that’s already manufactured in China and they want to buy it as is, then drawings aren’t needed.

But if the product is unique and made from a hard material such as metal, plastic, or wood, then engineer’s drawings are a must. It’s in your best interest to have drawings made because:

  1. You need an objective set of written standards to hold the factory accountable to. Not having drawings gives the factory a large amount of latitude to use the materials, dimensions, and tolerances that are convenient to them. With engineer’s drawings, the manufacturer in China is required to make your product to your specifications. Without drawings, a factory will make your product based on their best guess… I’ve rarely seen a case where a factory’s guess and the customer’s assumptions matched.
  2. You can’t get as prototype made without engineer’s drawings. Getting a prototype made to test from your drawings is a critical step of the development process.
  3. If your product or part must fit to another part, or is part of an assembly, it’s even more critical that you have drawings. Good engineer’s drawings must have all dimensions and tolerances, in addition to the material requirements, for every part. For example, if your part has a round male part with an outside diameter of .500 and needs to fit into a female part with an inside diameter of .510, the tolerances must be shown on the drawings to make sure the parts fit correctly. Depending on how tight the two parts have to fit, for example, the tolerance might look like this: O.D. of the male part: .500 +0/-.010. I.D. of the female part: .510, +/-.005. Without the tolerances, the factory won’t know how tightly the parts need to fit. This is especially important if you’re only having them make one part and they won’t see the part or assembly it would mate to.

To quote a product that requires engineer’s drawings, we prefer to get 2 dimensional pdfs that show all dimensions, tolerances, and material callouts, and step files (3 dimensional models) to start. While many domestic engineering firms use software like Solidworks, there are many Chinese manufacturing companies that don’t have this software. Every factory will be able to use 2D pdfs and step files so it’s the best way to get started. If a factory has other software and would prefer a different file format, they will request it.

I recommend that you do all engineering and prototyping in the U.S. The Chinese are great at manufacturing, but when it comes to design and development, they don’t have the same expertise or resources that U.S. firms do. We can buy just about any raw material or sample in a small quantity in the U.S., while they have a harder time with this in China. Also, the Chinese perception of what is appealing to the eye isn’t the same as what Americans prefer, their cultural preference and experiences are different.

If you don’t have engineer’s drawings but need to get them made, please contact us. We work with an excellent U.S. based engineering firm that can them made for you at competitive rates.