Free DFM Overview
A Design for Manufacturability (DFM) check for CNC-machined parts typically consist of a review of the design files and specifications to identify any potential issues that could affect the manufacturability of the part. Below you will find some specific aspects that may be reviewed during a DFM check for CNC-machined parts.
The designer should ensure that the tolerances specified in the design are achievable with the chosen CNC machining process.
Critical Tolerances We Review
- Dimensional Tolerances: These tolerances are typically specified as a range or a limit, and they ensure that the finished part meets the required specifications.
- Geometric Tolerances: These tolerances define the allowable variation in the shape of the part, including its straightness, flatness, roundness, and other geometric characteristics.
- Positional Tolerances: These tolerances specify the allowable variation in the location of features on the part.
- Coaxiality and Concentricity: These tolerances refer to the allowable variation in the center point of a feature or hole relative to its diameter.
- Angular Tolerances: Angular tolerances specify the allowable variation in the angle of a feature relative to a reference surface or axis.
- Material Selection: The material used for the part should be suitable for CNC machining, and the designer should consider the cost and availability of the material. Material properties such as hardness, strength, and ductility can affect the part's performance and should be specified as tolerances to ensure that the finished part meets the required specifications.
- Feature Size and Complexity: The designer should ensure that the part's features are suitable for the chosen CNC machining process and that the part's complexity is not too high for efficient and cost-effective production.
- Draft: refers to the taper or angle added to vertical walls or features of a part to facilitate its removal from the mold or CNC machine after manufacturing. In other words, it's the angle that is designed into a part to allow it to be easily released from the mold or tool without getting stuck. The draft is important because it can greatly affect the cost, quality, and manufacturability of CNC machined parts. Without a draft, a part may not be able to be removed from the mold or CNC machine, which can lead to damage or failure. Additionally, an insufficient draft can lead to increased cycle time, increased tool wear, and reduced tool life, which can increase the cost of manufacturing the part.
- Tool Access: The designer should ensure that the CNC machine can access all necessary features of the part during machining.
- Part Orientation: The designer should consider the best orientation of the part for efficient machining and to minimize material waste.
- Surface Finish Requirements: The designer should specify the required surface finish for the part and ensure that it is achievable. One of the main issues that needs to be considered is surface roughness. The required roughness will depend on the functional requirements of the part, such as the need for a tight seal or low friction. The surface roughness is typically specified using a roughness average (Ra) value.
- Edge and Corner Radii: The designer should ensure that the part's edges and corners have sufficient radii to prevent cracking or other defects during machining.
How Metal Craft Machining Handles DFM Reviews
Traditionally our industry has computer programs that can do a very rudimentary review of files that can spit out some data that many times isn’t very useful on complex parts. In our case here at Metal Craft Machining, we do not do that.
Our engineers will review the part, set up a time to do a 15-minute online screen share session with the customer to review the files, and then provide the customer report on what they discussed. Our goal is to demonstrate our value to existing and potential customers so that we get the chance to produce the part that we discussed.
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