When machine shops need to achieve the tightest tolerances for parts, plating can make or break their ability to meet those specifications.

At Focused on Machining, we take this responsibility very seriously. We’ve been burned by plating shops in the past, and we won’t risk letting it happen again. That’s why we only work with the best platers in the country. 

When you need your parts plated, you can count on us to select the right vendor, manage the entire process, and get your part done right the first time. 

Why Is Plating CNC Machined Parts So Risky? 

Tolerances are always measured post-plating. So we need to consider dimensional changes that may occur during this process before we begin machining. 

Low-risk plating processes like adding a thin coating to an aluminum part won’t change the dimensions at all. But as the thickness of the plating increases, the part will inevitably grow. This growth can affect tolerances. 

During regular anodizing, platers etch the part to remove a small amount of material before anodizing it. They typically replace only the etch of the part, moving it about 10% of our total tolerance. We have enough wiggle room with our tolerances that this minor part change usually isn’t a problem. 

Hard anodizing is where plating gets really risky. The plater adds so much growth to the part that we need to account for it during machining to ensure that it’s the right dimension post-plating. 

The Problem with Standard Plating Shops 

Because plating is such a complex and scientific process, it’s difficult to get it right. 

Plating consists of taking the parts, submerging them in a tank to clean them, transferring them to a tank of hot sulfuric acid, and calculating growth based on the surface area of the part. 

But for some of the parts we make, it’s impossible to calculate the surface area. The temperature of the tank, the electricity going into the tank, and the consistency of both variables can change the growth rate of the material.

Plating shops need the right people and the right processes in place to achieve the tightest tolerances. Unfortunately, many of them have neither, so it’s impossible for them to guarantee consistency and precision. 

Focused on Machining Guarantees High-Quality Plating for CNC Machined Parts

At our Denver machine shop, we won’t send your parts to just any plating shop. We have a well-vetted supply chain of vendors that we track and rate according to key performance indicators like quality and timing. 

We’ll be honest with you, the best plating shops do have longer turnaround times of up to 6 weeks. Sometimes the cost is even a little higher. But in our experience making parts with exceptionally tight tolerances, it’s always better to get the parts right the first time. 

If we send parts to a mediocre plating shop that rushes the process, there’s a good chance they won’t achieve the right tolerances and we’ll have to redo the entire order. We’ll never charge our customers extra money to make it right. But that’s a surefire way to miss a tight deadline!

When we need to hard anodize parts with tight tolerances, we like to send them to our preferred vendor in Chicago because they do such phenomenal work. 

We recently had an order for 150 tiny parts that had through-holes with exceptionally tight tolerances. Our customer wanted the parts hard anodized, which we knew would grow the material. We reached out to our preferred plating shop in Chicago before quoting the parts to see if they could achieve those tolerances and discuss our machining approach. 

We won the order and machined the parts according to the plater’s recommendations. We sent the parts to them to be hard anodized and they completely nailed it! All 150 parts came back to exactly the way our customer needed them. 
Don’t rely on just any machine shop’s vendor supply chain. When you need parts with tight tolerances plated to perfection, send them to our Denver machine shop. Request a quote for your next project!