Parts that passed machining inspection suddenly won’t assemble after anodizing — now your deadline is in danger and the supplier is blaming the coating.
If mating parts don’t fit after anodizing, the supplier likely missed machining allowances for coating growth — even 0.01-0.03 mm per side can turn a correct press fit into interference.
Keep reading to confirm whether the drawing or supplier process caused the failure — and how to recover fast. If needed, you can send us the drawing and out-of-tolerance parts for a thickness check and 24-hour rescue plan.
Table of Contents
Why don’t your mating parts fit after anodizing?
Because the machining was done to final dimensions instead of pre-coating dimensions, leaving no allowance for growth — the coating shrinks holes and enlarges shafts, eliminating the fit.
Most shops treat anodizing as a cosmetic step. They inspect before anodizing and assume everything will still fit. Once parts seize after coating, they either blame the tolerance or ask for redesign time you don’t have — because they never planned the allowance in the first place.
We machine to the final-after-coating dimensions and verify mating features after anodizing, so the fit performance is guaranteed at assembly, not just on the inspection report.
Supplier Takeaway:
If the parts fit before finishing and failed afterward, it’s almost certainly a process-planning mistake by the supplier. Send your parts and drawing — we’ll confirm allowance failure and propose a 24-hour recovery plan so you don’t lose another week arguing with the same shop.
How much thickness did anodizing add to cause your assembly failure?
Type II anodizing typically adds 0.01–0.03 mm per side, while hardcoat can add 0.05–0.125 mm per side — enough to instantly turn a safe clearance into a jam.
Coating thickness varies with color, time, alloy, and sealing. If the shop didn’t measure the finish thickness and relied on assumed values, your tolerance window was gone the moment the parts hit the tank — and re-anodizing won’t magically restore your intended fit.
We measure coating thickness per batch and adjust machining geometry using known growth behavior, so the final dimensions hit your fit class without surprises.
Recovery Takeaway:
If the coating added more than the available clearance, remaking the entire order is not the only option. Share your dimensions and anodizing spec — we’ll determine whether selective re-machining or controlled remake is the fastest path to working assemblies.
Can your supplier prove they planned for anodizing thickness before machining?
They can only prove planning if they machined to pre-coating dimensions and re-verified critical fits after anodizing. If the only inspection data is from before finishing, coating allowance was never engineered.
Most job shops treat anodizing as a cosmetic add-on and trust the anodizer to “make it work.” When fit fails, they ask you to wait while they “check with the finisher” — but nothing in their original plan included a check after coating.
We document what the final dimensions must be after finish, then confirm those fits when parts return — so assembly success is validated before anything ships out.
Supplier Takeaway:
If a supplier didn’t plan coating from the start, they won’t magically fix it now. Send the drawing and failed parts and we’ll give you a 24-hour verification and recovery plan, so you don’t lose another week on guesswork.
Need Replacement Parts Fast?
We start remachining or replacement immediately to protect your deadline
Who’s actually at fault — your drawing or the supplier’s anodizing plan?
If the drawing clearly states anodizing or finish requirements, final dimensions must comply after coating. If the supplier machined to nominal and let coating consume the clearance, that’s a process failure — not a design flaw.
Shops often push blame back, hoping you’ll relax tolerances to help them avoid rework. But relaxing specs only hides the issue — and guarantees a repeat failure the moment a fit becomes critical again.
We check finish call-outs, tolerance stack, and pre- vs post-anodizing dimensions to provide a clear root-cause report so reorders are correct the first time.
Accountability Takeaway:
Don’t redesign to cover your supplier’s mistake. Share your drawing and current inspection data and we’ll determine accountability and prevent another 2–3 week delay from a supplier “re-learning” your requirements.
How do you prove coating thickness exceeded spec and caused the fit problem?
Measure how much the coating added using eddy-current or cross-section tools and compare it against your available clearance and anodizing spec. If growth > clearance → mathematically proven cause.
Over-build happens often in blind holes, corners, and deep pockets that trap chemistry. If your supplier never measured thickness across the part, they cannot reasonably claim compliance — or offer a reliable recovery plan.
We map coating thickness at critical contact areas, then show how much interference was introduced so recovery choices are based on facts, not finger-pointing.
Proof Takeaway:
If your supplier hasn’t measured coating, they can’t fix coating failures. Send a couple failed parts and we’ll provide a thickness-fit analysis within 24 hours, so you can move forward instead of waiting for excuses.
Can oversized anodized parts be salvaged with post-coating machining?
Yes, oversized anodized parts can often be salvaged by light re-machining only at the interference areas, as long as the coating thickness and part geometry allow controlled removal.
This is the fastest way to rescue tight timelines when only a few features failed. However, most shops don’t offer this service because it requires precise fixturing and post-finish dimensional control. Asking the same supplier who caused the failure to fix it usually adds another week of uncertainty.
We evaluate the remaining coating and determine which areas can be selectively cut without exposing bare aluminum in functional regions. If it’s viable, rework can be finished within a day or two instead of restarting the entire part from raw material.
Recovery Takeaway:
If the majority of the part is correct and only a few features seized, selective re-machining can recover the entire order without major delays. Share your drawing and rejected parts and we’ll confirm whether a rescue re-machining plan gets your assembly working this week.
Should you strip the coating and re-anodize — or remake parts correctly?
Stripping and re-anodizing is only worth it when the base material and tolerances remain intact after stripping. If the initial machining ignored finish allowance, remake is usually faster and more reliable than chasing tolerance loss through multiple chemical cycles.
Stripping removes the finish but cannot restore the metal lost when tolerances were already consumed before coating. Re-coating on undersized or over-cut parts simply repeats the failure. Many shops propose stripping because it delays admitting machining was incorrect from the start.
We quickly assess whether material and geometry still support spec after stripping. If not, immediate remake prevents another multi-week slip caused by failed salvage attempts.
Decision Takeaway:
When coating failure comes from a flawed machining plan, stripping only burns more time. Send us the inspection report and finish spec and we’ll confirm whether remake or salvage gets working parts in hand without repeat issues.
What’s the fastest way to rescue your project after anodizing fit failure?
The fastest recovery path is to isolate only the failed fits and determine if they can be re-machined within tolerance. Full remake is a last resort. The key is acting before another batch goes through finishing and loses another week.
Waiting for the same supplier to “try another run” typically means your timeline slips while they repeat the same process that already failed. A fresh evaluation that includes coating thickness measurement and remaining-material checks ensures every step moves forward, not backward.
We prioritize projects in this exact situation by performing post-coating fit verification within 24 hours, identifying the quickest fix: selective re-machining, controlled remake of only critical features, or a rapid re-order of the parts that have no viable salvage route.
Urgency Takeaway:
If you’re stuck waiting for your supplier’s next attempt, the real risk is lost time. Share your drawings and two sample parts and we’ll give you a confirmed fastest-path plan before another day slips.
How fast can a new vendor remachine or replace parts without repeating failure?
A capable shop can confirm a recovery path within 24 hours and complete re-machining in 1–3 days if geometry allows. If remake is required, 5–10 days is realistic for most CNC aluminum components — as long as the correct coating allowance is engineered up front.
The danger isn’t the machining time — it’s trusting the same supplier who already missed the coating allowance. They usually ask for more time to “re-evaluate,” which is code for repeating the same approach and slipping your assembly schedule further.
We start by confirming how much coating growth caused the issue, then apply finish allowance into the new NC program or rework strategy before cutting anything. That means the rescue cycle closes once — not twice.
Turnaround Takeaway:
If your supplier cannot define a guaranteed timeline tied to a corrected process, every extra day is a gamble. Send your drawing and two failed samples and we’ll provide a 24-hour rescue timeline you can take to your project manager with confidence.
How do you verify a new supplier won’t repeat the same anodizing fit mistake?
Ask whether they will inspect and confirm mating fits after anodizing — not just before. If they only guarantee pre-finish dimensions, they are not managing coating growth.
You need a shop that programs around final dimensions, checks coating thickness on every batch, and treats finishing as part of the dimensional process. The more critical the fit, the more important that machining and anodizing are controlled together — not thrown over the wall to a finisher and forgotten.
We measure the coating and re-verify critical dimensions after anodizing because the final numbers are the only ones that matter when you try to assemble.
Qualification Takeaway:
If a shop cannot show exactly how they engineer coating thickness into critical fits, they are asking you to trust luck twice. Share your fit requirements and we’ll demonstrate our post-finish fit validation so you never repeat this delay.
Not Sure If These Parts Can Be Saved?
Upload drawing + failed dimensions — we confirm salvage options in 2 hours
Can you re-machine anodized parts to correct dimensions — or start over?
You can re-machine anodized parts if the interference is small and the feature geometry allows clean tool access. But if coating thickness consumed too much tolerance or the interference is deep inside pockets, remake is usually faster and more reliable.
A good shop won’t guess. They’ll confirm how much coating can be safely removed without exposing bare aluminum in areas where corrosion or appearance matters. If qualification timelines are tight, trying to rescue an unsalvageable batch is worse than restarting immediately with the right allowance.
We decide based on remaining material, coating thickness, and the part’s role in the assembly — so the recovery plan is built on certainty.
Recovery Takeaway:
If your current vendor can’t commit to a single-cycle fix, you risk losing more weeks. Send us the drawing and critical fits and we’ll tell you today whether re-machining or remake is the fastest path to a correct build.
Should you switch to a supplier who handles machining and anodizing in-house?
Switching to a shop that controls machining and anodizing together is the most reliable way to guarantee final fit — because coating growth is engineered up front and verified after finishing.
When machining and finishing are disconnected, both vendors assume the other will protect the tolerance — and you end up managing blame instead of progress. Owning the entire stack eliminates the classic “pre-finish inspection was fine” excuse and ensures coating allowances are baked into the first setup.
We coordinate coating from the CAM program through final inspection so the numbers in your drawing are the numbers that assemble in real life.
Action Takeaway:
If the root cause is process disconnection, changing suppliers is the only way to protect your deadline. Share your drawings and failed parts now — we’ll deliver a controlled plan and replacement timeline within 24 hours, so this is the last restart you make.
Conclusion
Your assembly is waiting. Don’t lose another week hoping the same supplier suddenly fixes a process they never engineered. Send your drawing and two failed parts now — we’ll confirm cause, give you a recovery plan within 24 hours, and get parts that actually fit.
Frequently Asked Questions
Not unless the original drawing omitted finish requirements. If the dimensions include anodizing, the process must deliver compliance — not compromise.
Choose a shop that controls machining and anodizing together, and inspects fits after coating — the only dimensions that matter are the ones at assembly.
Typical remake time for aluminum CNC parts with anodizing is 5–10 days, once finish allowance is engineered correctly. We’ll confirm your exact timeline in 24 hours.
We analyze sample variation first. Often, only critical fits need rework or remake, not the entire batch — saving both time and budget.
Yes. We capture color parameters from your parts and reuse the same coating system so replacements blend seamlessly into the assembly.
Only in the exact areas we remove interference. We verify whether remaining coating fully protects functional and visible surfaces before recommending rework.
