June 2024

In our industry, achieving precision is the ultimate goal. But what happens when precision comes at a higher-than-necessary cost?

Understanding the difference between machining and fabrication tolerances is crucial for ensuring cost-effective and efficient production processes. Allow us to shed light on the nuances of machining and fabrication tolerances and reveal how to ensure your parts are the best value for your necessary end use.

Machining Tolerances vs. Fabrication Tolerances

One of the primary sources of confusion for customers involves understanding the difference between machining and fabrication tolerances. Here are the notable distinctions:

Machining Tolerances

Tighter tolerances often translate to higher precision and accuracy in machining. These tolerances typically require specialized equipment, meticulous setup, and skilled operators. As a result, parts with tight machining tolerances tend to be more expensive to produce due to the increased complexity and precision involved. 

Fabrication Tolerances

Fabrication tolerances, however, are often more lenient, as there is more variability associated with metal fabrication processes like bending, forming, and welding. While precise dimensional control is still essential in fabrication, factors such as material behavior, welding distortion, and assembly requirements influence the allowable tolerances for fabricated parts.

The Pitfalls of Overtoleranced Parts

Because this distinction is not always clear, customers may inadvertently specify tolerances far tighter than what their project actually requires. Often, engineers want to exercise caution – they figure it’s better to have an over-toleranced component than one that doesn’t meet the nominal. However, applying too-tight tolerances to parts can be detrimental. Here’s how:

• Higher costs: Over-tolerancing parts can significantly inflate costs, leading to overpriced quotes. Many of our customers experience sticker shock before contacting MFP for clarification, only to learn that loosening their tolerances can cut their costs in half without impacting the quality of the end product. 
• Missed opportunities: When customers request extremely tight tolerances in their request for quote, there’s a good chance contract manufacturers may no-quote the part because they don’t want to take on the risk of a scrap or rework involved with such close precision. 

How to Bridge the Gap Between Precision and Affordability

Meeting quality standards while ensuring cost efficiency is certainly a balancing act. However, putting the following strategies into practice makes it possible.

Consider the Component’s Intended Application

When determining the tolerancing requirements of each part, it’s crucial to align tolerances with the part’s end use. Rather than designing the most perfect part possible, customers should aim for tolerances that meet the functional requirements of their parts. That way, they can ensure cost-effective solutions without compromising quality or reliability.

Provide Accurate Information Upfront, When Possible

Ultimately, the goal is to avoid unnecessary expenses by providing accurate and comprehensive information upfront. Customers who provide detailed specifications and understand the capabilities of manufacturing equipment are more likely to receive competitive quotes that accurately reflect their needs.

Establish Clear Communication with a Trusted Supplier

Customers can secure competitive pricing and efficient manufacturing solutions by understanding the intricacies of machining and fabrication tolerances and providing precise specifications.

The Metal Fabrication Professionals team is happy to demonstrate the capabilities of different manufacturing processes and the associated costs so they can make informed decisions that balance precision with cost-effectiveness. Our personalized approach to fabrication and machining services offers customers the resources they need to bridge the gap between affordability and precision.

Request a quote to partner with our expert team.