Precision and accuracy are critical for the function of many products. The individual tolerance ranges of each component create a cumulative tolerance for the assembled product, so if the assembly tolerance must be precise, the parts that make up the assembly must be even more precise. Design for Manufacturing (DFM) practices can ensure your precision metal stamping parts meet the tolerances you need for the final assembly.
What is DFM?
DFM is an engineering and product design concept that involves creating products to optimize their manufacturing process. By considering manufacturing constraints early in the design phase, engineers can ensure that the product can be efficiently and cost-effectively produced. It aims to reduce product complexity, minimize defects, and improve overall product quality while reducing manufacturing times and costs. It also ensures that functionality, reliability, aesthetics, regulatory compliance, and customer satisfaction meet expectations.
The history of DFM is one of incremental changes through the decades. As technology advanced and products became more complex, it became clear that the traditional methods of designing a product first and then figuring out how to manufacture it later was highly ineffective. It wasn’t until the 1990s that design for manufacturability as an engineering discipline became formalized with processes for a wide range of product types.
Benefits of DFM for Precision Metal Stamping
It’s been said that 70 percent of the product cost is determined during the development phase, but engineering changes during the manufacturing phase can inflate your product costs and severely impact profitability. It is much more cost effective to design the part holistically, considering manufacturing, assembly, and even maintenance. Precision metal stamping is a process that can benefit from implementing DFM principles. Here are a few areas where DFM can make an impact:
Material Waste – Optimizing your design for stamping results in less material waste. Parts can be optimally nested to reduce material waste.
Production Costs – Since DFM is a holistic process that looks at more than just the part design, it can reduce production costs by removing or improving elements that make production or assembly challenging. It can also minimize the number of components required for assembly.
Quality Issues – DFM can reduce the risk of quality issues, such as defects or errors, before parts are produced, preventing scrap, reworks, and lost time and money.
Time to market – When processes are streamlined through part modification early in development, time to market decreases and profitability increases.
Product Performance – DFM may increase product performance, resulting in increased customer satisfaction and potentially higher sales.
Product Lifespan – When DFM principles are applied, the result can be more durable and longer-lasting products, reducing the need for costly repairs or replacements.
Precision Metal Stamping DFM
Engineers will want to know everything about your product and its use before making any changes. Some of the questions they may have include:
What are the physical requirements for the part – strength, durability, etc.? There may be a less expensive material that will provide what you need.
What environments will the part be exposed to, and how is it used? This will also help with material selection as well as any finishing or plating requirements.
How do components interact with each other? Can we combine any to remove costs?
How are parts assembled and maintained? Do parts need to come apart for maintenance? Can fastener insertion be done in die, or do they have to be welded? Will in-die clinching or staking work?
Are non-critical features stated? Unnecessary precision can add costs.
If you have multiple products, can similar components be standardized to be used across all of them?
Can components be designed to be used on only one orientation when possible to mitigate the risk of improper assembly?
In addition, engineers will look at part complexity and tolerances to ensure their equipment can stamp the part efficiently and remove secondary operations when possible. Each type of metal will react differently and may have different degrees of resistance to bending, punching, and forming, so the engineer will need to understand the limitations of the material and make adjustments. In general, with the understanding that these can vary depending on the material being used, here are just a few basic guidelines engineers will follow.
Holes and slots – The diameter of tight tolerance holes and slots generally must be equal to or greater than the material thickness. However, this can vary with materials that have a high sheer strength. Holes and slots require a minimum distance of about twice the material thickness between each other or the edge of the part to prevent a bulging of the material. When near a bend, the distance should be 1.5 times the material thickness plus the bend radius. Punched holes have a slight taper, so if precision is required on both sides of the holes, a secondary operation may be needed.
Flange – The minimum width of a flange should be 2.5 times the thickness of the material.
Bend – Generally, the inside bed radius should be at a minimum equal to the thickness of the sheet metal and should bend in one orientation. The overall height of a bend should be at a minimum of 2.5 times the thickness of the material plus the radius of the bend. The material may tear if a bend is made close to an edge. To prevent this, the part designer may need to include an offset that is at least equivalent to the material thickness. Alternatively, bend relief notches can be used.
Corners – Blank corners should have a radius of at least half the material thickness.
Embosses – Embosses are created by stretching the material, and excessive depth can lead to thinning or fracturing. The maximum depth should be less or equal to three times the material thickness.
These are just a few considerations when designing a precision metal part for stamping. Working closely with your metal stamping partner during the design phase will ensure you receive a finished part that cost-effectively meets your expectations.
Speak to the Precision Metal Stamping Experts at Die-Matic
To ensure you receive a quality precision part at a competitive price, Die-Matic applies DFM principles to every part. Let us guide you toward the ideal product design for efficient manufacturing and assembly. Whether enhancing your original design or streamlining for cost savings, our expertise will make all the difference. Contact us to get started.