China Manufacturing parts DFM Feedback Glossary

When you upload a part to the China Manufacturing parts, Inc. platform, you receive instant design for manufacturability (DFM) feedback. Here are some explanations for why you received that feedback and what you can do to get your part ready to machine!

Fillets to be added

Explanation

Fillets will be added to sharp internal corners or areas where drafted or sloped edges meet sharp edges. Otherwise, these features are impossible to machine. 

Action Step

If you want to specify radii on your fillets, you can add them to your design. Otherwise, the manufacturer will use their discretion to add fillets to these areas.

Fillets to be increased

Explanation

The fillets that are designed into your part are too small to be machined with the smallest end mill that would otherwise be necessary. This adds an extra tool and tool change operation to the CNC machining program, adding time to the overall project. 

Action Step

No action required, unless you want to change the fillets to be a specific size. Otherwise, the machinist will increase the fillet size to avoid using an extra tool. 

Depth of hole (drilling)

Explanation

If the depth of a hole in your part is greater than 12x the nearest bit diameter, we will not be able to machine your part. Drills that are greater than 12 times the diameter of the bit are hard to source and may break during drilling. If you increase the diameter of the hole, a larger drill can be used, which would mitigate the issue. 

Action Step

If the hole is a blind hole and is too deep to be drilled, you can try to decrease the depth of the hole or increase the diameter of the hole. The ratio of depth to diameter needs to be less than 12.

Depth of cut (milling)

Explanation

If the depth of a feature in your part is greater than 10x the diameter of the end mill used, we will not be able to machine your part. End mills that are greater than 10 times the diameter of the bit are hard to source and may break during use. This may occur if you have thin but deep features such as slots or grooves. 

Action Step

If you can, decrease the depth of the feature. Otherwise, increase the feature diameter or the corner radius (fillet), which will allow a larger diameter tool to be used. This in turn allows a longer tool. 

Non-standard thread (produced at risk)

Explanation

The fit/function of this thread size cannot be guaranteed because we cannot source a proper thread checker. We can still move forward with manufacturing your part, but it will be a High Risk Product. 

Action Step

In order to guarantee the fit and function of your threads, you can select a standard thread size. 

Thin walls may not hold up to machining

Explanation

Our minimum required thickness is 0.25mm for metals and 0.50mm for plastics. If the wall is any thinner than this, they will not hold up to the manufacturing process. The material may warp, deform, or break altogether. To move ahead with manufacturing, you will have to update the wall thickness to be above the minimum.

Action Step

The minimum required thickness is 0.25mm for metals and 0.50mm for plastics. Update your design to be above the minimum thickness of your material.

Warping may occur if too much material is removed

Explanation

Removing a large amount of material from a part puts a lot of stress on the workpiece, causing warping when the part is removed from the machine.

Action Step

Evaluate the design of your part (is it best suited to CNC machining?) and the geometry of the final part (thin walls). Add to the wall thickness or consider changing the manufacturing process.

Not optimized for CNC machining

Explanation

Your part is not optimized for CNC machining. Significant changes must be made for it to be manufactured.

Action Step

Chat with a China Manufacturing parts, Inc. representative to learn more about why your part failed for CNC machining. 

Part will be reworked from McMaster part number

Explanation

Your part will be manufactured from a specific McMaster part number. This may be stock material that is purchased from McMaster.

Action Step

You don’t have to do anything, unless you have issues with the part number listed. In that case, contact your China Manufacturing parts, Inc. sales rep.

Manual deburring may be necessary

Explanation

The highlighted areas may be deburred manually due to reachability constraints or the necessary tool geometry required. Some areas may have chamfers that are not accessible with standard tooling. In this case, these areas will be deburred manually.

Action Step

If you don’t want these features to be deburred manually, you can remove the chamfers from your CAD model. 

Thin stock not available for chosen material

Explanation

Due to the part thickness, this part must be made from stock thickness material. However, the thinnest material available is too thick. If we do machine with your desired thickness, the part will end up warped or out of spec. 

Action Step

Reconfigure your part with an alternate material (suggested in your DFM feedback). You can also chat with a China Manufacturing parts, Inc. rep for more recommendations. You can also change the thickness of your design to be the minimum thickness available for your required material. 

Non-matching drawing and CAD model

Explanation

The CAD model does not match the 2D drawing you provided. 

Action Step

If your CAD model is correct and you don’t need a 2D drawing, you can simply remove the 2D drawing. Otherwise, you can upload the correct CAD model that does match the 2D drawing. You can also generate a 2D drawing right on China Manufacturing parts’s platform.

Material mismatch

Explanation

Your material configuration does not match your 2D drawing. We cannot make your parts with this conflicting information.

Action Step

If your drawing states the correct material, reconfigure your part with the correct material. Otherwise, annotate your drawing to cross out the material and make a note of the correct material. 

Unreachable volume

Explanation

This feature is not fully accessible or machinable with standard tooling. Either it is too deep, at an angle, or obstructed by another feature. 

Action Step

In order to make the feature(s) machineable, please update your model so that the necessary features are reachable. Talk to your China Manufacturing parts, Inc. sales rep for more details.

EDM may limit lead time options

Explanation

Due to the design, this feature will be machined with electrical discharge machining, so it is only able to be produced overseas. This may limit the lead time options. 

Action Step

If you require a different lead time or to manufacture domestically, please update your model so that it can be machined using standard tooling. 

Gear hobbing may limit lead time options

Explanation

This feature will be machined using gear hobbing, so it can only be produced overseas. This may limit the lead time options.

Action Step

If you require a different lead time or to manufacture domestically, please update your model so that it can be machined using standard tooling. 

Tight tolerance plastics

Explanation

Tight tolerances below a bound of 0.1mm in plastics cannot be guaranteed. Plastic materials can warp due to temperature changes while machining, so we cannot hold tolerances below +/-0.05mm. PEEK has the best dimensional stability with temperature changes and may be a good alternative if your tight tolerances are critical.

Action Step

If you do nothing, parts will still be machined but we cannot guarantee the tight tolerances. If these tolerances are critical, you can change your material to PEEK.

To learn more about best design for CNC machining, check out Fictiv’s DFM Masterclass!