DFM Guidelines to Simplify Manufacture

Design for Manufacturing (DFM) integrated into the product design simplifies the manufacturing process. The goal is to design a product that can be easily and economically manufactured. The importance of DFM is highlighted by the fact that around 70% of manufacturing costs of a product (cost of materials, machining, and assembly) are determined by design decisions, with manufacturing decisions (such as process planning or machine tool selection) responsible for only 20%. DFM guidelines help the design team to simplify product manufacture and therefore overall project costs.

Below is a list of DFM guidelines:

1. Reduce the total number of parts
By reducing the number of parts in a product design, this provides the best opportunity for reducing manufacturing costs. Fewer parts mean less engineering development time, purchases, inventory, work-in-processing time, fabrication and assembly steps, inspection, etc. Overall it reduces the level of intensity of all product-related activities. The design teams focus is to evaluate each part to see if it can be eliminated, combined with another part or its function can be performed in a simpler way. Does the part move relative to other moving parts. Does the part have to be made of a different material from the other parts.

2. Standard components plus common parts and materials
Design using "off the shelf" standard components that are less expensive than custom-made items and they simplify the design. Common parts and materials will reduce inventory, costs and product lead times.

3. Design for ease of fabrication
Select processes compatible with the materials and production volumes. Select materials compatible with production processes that reduce processing time but meet functional requirements. Final surface requirements such as painting, polishing, finish machining, should be clearly understood and design intent accurately defined.

Guidelines to be considered during design:

Design of tolerances to be within manufacturing capabilities
Continually designing for manufacturing will improve product quality and reduce fabrication costs. After completion of preliminary drawings, meet with manufacturing and review design intent, requirements and determine manufacturing process requirements. Manufacturing to review tolerances and determine process capabilities to meet dimensional limits. In general, the design to avoid unnecessarily tight tolerances that are beyond the natural capability of the manufacturing processes. Determine when new production process capabilities are needed early to allow sufficient time to determine optimal process parameters and establish a controlled process. Tolerance stack-ups should be considered on mating parts. Overall assembly tolerances should be calculated, and interface as well as clearance requirements understood.

CAD Software 3D Modeling to evaluate product design
With today’s advances in PC & software power, using CAD software for example Autodesk Inventor is a very powerful tool to evaluate your product design. This is a good time to pull the design team and manufacturer together to demonstrate and evaluate the product parts, subassemblies & assemblies. This will allow the review of the majority of the above DFM guidelines and most importantly how the physical-relationship of the parts work together when viewed as a 3D model.