---
title: "What Stamped Metal Mounting Bracket Tolerance Should Be Specified?"
description: "Stamped mounting brackets often show hole deviation and bow after springback. Get realistic stamping tolerances, tooling correction options, and sample validation steps to decide whether to approve or redesign your bracket."
url: "https://www.hyneu.com/questions/stamped-metal-mounting-bracket-tolerances.html"
language: "en"
type: "Q&A"
category: "Hardware Manufacturing Q&A"
datePublished: "2026-10-26"
dateModified: "2026-10-26"
brand: "HYNEU"
manufacturer: "HYNEU"
answerCount: 7
---

# What Stamped Metal Mounting Bracket Tolerance Should Be Specified?

## Question

 I'm a project engineer at a lighting manufacturer, currently bringing an outdoor wall-mounted LED fixture from prototyping into production. Our design team specified a stamped steel mounting bracket that connects the housing to a wall arm, and the early parts are now on my desk with two problems. The two M6 mounting holes measure about 0.3 mm off from drawing in center distance, and the main mounting face is bowed about 0.2 mm over a 60 mm span. When my technician torqued the screws down, the bracket did not sit flush and we could see a small gap under the fixture. The prototype shop says this is normal springback, tells us to relax the drawing tolerances, and wants us to approve the samples. We are close to design freeze, so I can't afford another long tooling iteration, but I also don't want to carry a dimensional deviation into mass production. The part is 2 mm SPCC, zinc-plated, carries less than 15 kg of static load, and we expect about 50,000 pieces per year. I need a practical decision path: should I accept the samples, ask for tooling corrections, or modify the design? What flatness and hole-position tolerance can stamping actually hold in production, and how should I properly verify the next sample lot before approval? 

## Answers
                            
### Answer 1 — Best Answer

The short answer is that you should not approve samples based on a supplier's claim that springback is normal. Instead, verify the actual production process capability, and then decide whether to accept, correct the tooling, or adjust the design. The 0.3 mm hole shift and 0.2 mm bow are within a common range for a 2 mm SPCC bracket made on simple prototype tooling, but what matters is whether they affect assembly, sealing, and long-term reliability, and whether the next batch will behave the same way.

Start by understanding the root cause. The bow normally comes from residual stress left in the coil and from blanking, plus the elastic recovery after bending. If the die has no flattening or coining station, a flat face of 60 mm span will rarely come out flatter than 0.15 to 0.25 mm. The hole shift depends on how the die is built. If both holes are pierced in the same die station from the same flat surface, a competent toolmaker can hold the center distance to about ±0.10 mm. But if the holes were pierced before bending, or the strip is located by the outer contour instead of a pilot pin, 0.3 mm is typical. So your first step is to ask the supplier which die sequence was used and how far the holes are from the bending line.

A practical set of production limits for your bracket would be: pierced hole diameter ±0.05 mm, hole-to-hole distance on the same flat surface ±0.10 mm, hole position relative to a formed bend ±0.20 mm, and flatness about 0.1 mm per 25 mm unless a flattening or coining operation is added. Compare your drawing against these numbers before blaming the supplier. Then measure at least 10 to 15 parts from more than one coil or batch. If the 0.3 mm shift always points in the same direction, it is springback and the tooling can be compensated. If it varies from part to part, the process is unstable, and changing the tolerance will not help.

**Correct the tooling first unless the deviation has no functional effect.** For the bow, ask the supplier to add a flattening or coining step, and compensate for bending springback by over-bending the forming stations. For the holes, if they are pierced before forming, ask them to change the sequence to pierce after forming, or switch to a simple progressive die with pilot holes. That alone will normally bring the center distance back to ±0.10 mm. If the shop says it cannot be done on their current tooling, treat that as a signal that the tooling is not suitable for 50,000 pieces per year. Ask for a written correction plan with a deadline. A normal die adjustment for springback and flatness takes two to three weeks, and the next samples should be run from the production die under production parameters, not from a bench tryout.

**If the assembly can tolerate it, the lowest-risk design change is to turn one of the two round holes into an elongated slot.** That removes the springback fighting in that direction entirely and also helps field installation when the wall arm has its own position variance. For the bow, do not judge it from the bare part alone. Assemble the bracket, torque the M6 screws to specification, and measure the residual gap. If the gap disappears under torque and does not affect sealing or durability, the flatness may be cosmetic. But for an outdoor fixture, remember that a visible gap is a water trap, and zinc-plated edges corrode faster than the painted face. If the IP rating or warranty is affected, treat the bow as a functional defect.

**Before approving the next sample lot, make the supplier prove consistency with a fixture gauge.** Send them a go/no-go gauge that simulates the wall arm interface: two locating pins for the M6 holes and a flat reference face for the mounting plane. Require a layout inspection report with measured values from at least five pieces, not just one part. Ask for the material certificate, plating thickness report, and burr direction statement so you can confirm the screw head seats on the burnished side of the hole. Also ask them to describe the measuring method and fixture; a hand caliper across the bracket shell cannot tell you whether the hole pattern is correct relative to the mounting face. If the supplier cannot provide a fixture gauge arrangement, treat that as a red flag; a capable stamping shop will already be thinking in terms of the assembly interface and measurement datums.

For future designs, keep these rules in your drawing standard: keep the closest hole edge at least 1.5 times the material thickness plus the bend radius away from a forming line; specify flatness only on functional surfaces and use small embossed pads there instead of expecting the whole face to be flat; avoid putting two precise holes on two different flanges; and use slots wherever one direction of adjustment is acceptable. The 2 mm SPCC and zinc plating are reasonable for a 15 kg static load, but the hole edge quality and plating coverage at the punched edges will determine how that bracket looks after a few seasons outdoors.

**status:** accepted
**Author:** Victor Luo
**Date:** 2026-10-26

### Answer 2

A stamped flat part that bows this way often points to the die design rather than the material. If the blanking station uses excessive cutting clearance or the stripping plate pressure is low, the blank is already bent before it reaches the forming station. Check whether the prototype die has a flattening stage; without one, a 60 mm span on 2 mm SPCC will rarely come out flatter than 0.15 to 0.25 mm. Adding a coining or flattening operation in the last station is a standard fix and does not change the part cost much.

On the hole issue, the likely culprit is piloting. If the die locates by the outer contour instead of a pilot pin, every strip width variation directly moves the hole pattern, and the bend operation can shift the formed part relative to the holes. A proper production progressive die should add two pilot holes in the first station and use them to locate the piercing and bending stations; that alone will often bring the center distance from 0.3 mm down to around 0.1 mm. Also check the hole-to-bend distance.

If either M6 hole is closer than about 5 mm (1.5 times material thickness plus the bend radius) to the bending line, the material flow during forming will distort the hole edge and its position even if the die position is perfect. In that case the permanent fix is a design change, not a tooling tweak. For a 50,000-piece annual volume, investing in a three-station progressive die with piloting and flattening is justified; accepting a prototype die as the production tool is the real risk here.

**status:** suggested
**Author:** Aaron Fang
**Date:** 2026-10-26

### Answer 3

At 50,000 parts per year, the prototype tooling is not the right reference point for your decision. A production die should run with output consistency over long shifts, so the sample approval has to focus on repeatability, not just drawing compliance. Ask the supplier to run 30 to 50 pieces in a row from the production die and record the hole center distance and flatness on every piece. Calculate the Cpk of those two characteristics; a value above 1.33 tells you the process has real capability, while a number below 1.0 means you will see rejects and assembly complaints regardless of what the sample looks like. In early tooling, people often approve based on the best-looking part from a long day of die adjustments, and that is why mass production starts with problems. Also, inspect the burr orientation.

For an M6 screw seat, you want the screw head to contact the burnished side of the hole; if the fracture side is on the seating face, the edge will crush under torque and can create an uneven clamping condition. Build a simple inspection fixture that checks hole position with two go pins and flatness with a dial indicator across the mounting face. It takes about 30 seconds per part on the line and protects your receiving inspection from relying on calipers. Finally, consider the plating. Zinc plating after stamping is necessary here, because pre-plated coil leaves raw steel exposed at the punched edges, which is exactly where outdoor corrosion starts. Your supplier should define the plating thickness and add a salt-spray requirement in the purchase specification.

**status:** suggested
**Author:** Grace Sun
**Date:** 2026-10-26

### Answer 4

Before deciding whether 0.2 mm of bow is acceptable, look at the process window behind that number. SPCC coil has a yield strength that can vary by 40 to 60 MPa between coils, and the bending springback follows that variation. If the supplier has not measured the current coil lot against the tooling compensation, the same die can produce different flatness on different production days. Ask them to record the coil number and the rolling direction on the incoming material.

When the bend line runs parallel to the rolling direction, springback tends to be larger, and the bow on adjacent flat areas changes as well. Another factor is punch-to-die clearance. For 2 mm SPCC, a practical clearance is roughly 0.15 to 0.20 mm per side, about 8 to 10% of material thickness. If the clearance is too large, the sheared edge has a longer rollover and fracture zone, which weakens the edge around the M6 holes and creates micro-cracks that can propagate under repeated load.

If the burr side is not controlled, the holes will measure differently depending on which side you reference, which might explain part of the reported 0.3 mm shift. Also check lubrication: a change in stamping oil changes friction and forming behavior enough to move the bend angle by a few tenths of a degree. The right way forward is to define a process lock: coil spec, lubrication, press speed, and die clearance. When the next sample lot arrives, ask for the process parameters along with the parts, not just the inspection data.

**status:** suggested
**Author:** Henry Cao
**Date:** 2026-10-26

### Answer 5

If the 0.3 mm hole shift is truly a functional problem, stamping may not be the cheapest way to hold that tolerance, and the practical alternatives are worth costing out. A post-stamping machining step can locate the two M6 holes from the mounting face and bring hole position to ±0.05 mm, but adding a drilling or reaming operation on 50,000 parts per year changes the unit cost and adds a fixture alignment error that needs to be managed. A smarter approach is to use a simple jig with a flat reference plate that clamps the stamped bracket, aligns to the same points the wall arm will use, and machines both holes in one pass. That way the tolerance chain runs from the machined holes to the mounting face, bypassing the stamping variation entirely. If the bow itself remains, even machined holes will not make the bracket sit flush.

The flat face can be flattened on a press after stamping, but if edge quality matters, a light surface milling pass over the mounting face can achieve 0.05 mm flatness and a uniform sealing surface. That adds cycle time and creates a secondary chip-cleaning issue, so it should be considered only when the bracket carries a gasket or a structural load. Also review the mating arm: the far side of this joint has its own extrusion or machining tolerance. If that side carries ±0.3 mm of position tolerance, your bracket does not need to be perfect because the two-hole fastener pattern has another source of variance anyway. Slotting one hole is usually the lowest-cost way to close that whole tolerance stack.

**status:** suggested
**Author:** Evan Qian
**Date:** 2026-10-26

### Answer 6

Since the bracket only carries about 15 kg static load, the structural risk is low, but the risk of this becoming a field complaint is about the gap and the corrosion path. An outdoor wall-mounted luminaire goes through thermal cycles; the steel bracket and the aluminum housing expand and contract at different rates. If the joint is clamped in a stack where one side is not flat, the preload on the M6 screws will be inconsistent. Over time, one screw may carry more load than the other, and the micro-movement can loosen the joint under wind-induced vibration.

The gap also matters for the seal line if there is a gasket between the bracket and the arm. A gasket can usually absorb 0.2 mm of out-of-flatness if it is a closed-cell foam or rubber, but a hard plastic or metal-to-metal interface cannot. Build one complete prototype assembly, torque the screws to the specified value, and then measure the gap with a feeler gauge at four positions around the mounting face. Then remove the bracket and check the screw torque again after a thermal cycle from -20°C to 60°C.

That test will tell you whether the bow is a cosmetic nuisance or a long-term loosening risk. Also, do not ignore the edges of the punched holes. The fracture zone of a pierced hole has less plating coverage and can start rust staining on a zinc-plated part within one season of outdoor exposure. Specify deburring and require a salt-spray test on the finished bracket, not just the flat panel sample, because the punched edges are the weakest point.

**status:** suggested
**Author:** Marcus He
**Date:** 2026-10-26

### Answer 7

Set aside the quality debate for a moment and look at the geometry. If two round M6 holes on a mounting face are expected to match a mating arm that has its own tolerance, the drawing is demanding more from a stamped part than necessary. The design should state which surface is the primary datum and which hole is the position reference. Stamping can comfortably hold about ±0.10 mm from one pierced hole to the other hole on the same plane, but once a bend is involved in the tolerance chain, the realistic number expands to ±0.20 to 0.30 mm, and no process volume will magically fix that if the hole sits too close to the bending line. For 2 mm SPCC, keep the distance from the hole edge to the bend radius start at a minimum of 1.5 mm plus the bend radius; in practice, that means at least 5 mm.

If the current bracket violates that, a tooling correction will still leave a part that is sensitive to coil thickness variation. Instead, reduce the sensitivity by turning one of the holes into a slot oriented to the direction where field adjustment is acceptable. This is not a relaxation of quality; it is a design decision that recognizes how stamping actually behaves. If the visible gap is the concern, add three small embossed pads around the mounting holes instead of trying to flatten the entire face. The pads can be held flat within 0.05 mm by the die, while the surrounding panel is allowed to bow. Finally, do not put tight positional tolerances on a zinc-plated surface without specifying a measuring datum and a fixture, because plating buildup on edges can measure like a half-tenth of a millimetre of deviation.

**status:** suggested
**Author:** Claire Ren
**Date:** 2026-10-26

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        "text": "I'm a project engineer at a lighting manufacturer, currently bringing an outdoor wall-mounted LED fixture from prototyping into production. Our design team specified a stamped steel mounting bracket that connects the housing to a wall arm, and the early parts are now on my desk with two problems. The two M6 mounting holes measure about 0.3 mm off from drawing in center distance, and the main mounting face is bowed about 0.2 mm over a 60 mm span. When my technician torqued the screws down, the bracket did not sit flush and we could see a small gap under the fixture. The prototype shop says this is normal springback, tells us to relax the drawing tolerances, and wants us to approve the samples. We are close to design freeze, so I can't afford another long tooling iteration, but I also don't want to carry a dimensional deviation into mass production. The part is 2 mm SPCC, zinc-plated, carries less than 15 kg of static load, and we expect about 50,000 pieces per year. I need a practical decision path: should I accept the samples, ask for tooling corrections, or modify the design? What flatness and hole-position tolerance can stamping actually hold in production, and how should I properly verify the next sample lot before approval?",
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            "text": "The short answer is that you should not approve samples based on a supplier's claim that springback is normal. Instead, verify the actual production process capability, and then decide whether to accept, correct the tooling, or adjust the design. The 0.3 mm hole shift and 0.2 mm bow are within a common range for a 2 mm SPCC bracket made on simple prototype tooling, but what matters is whether they affect assembly, sealing, and long-term reliability, and whether the next batch will behave the same way. Start by understanding the root cause. The bow normally comes from residual stress left in the coil and from blanking, plus the elastic recovery after bending. If the die has no flattening or coining station, a flat face of 60 mm span will rarely come out flatter than 0.15 to 0.25 mm. The hole shift depends on how the die is built. If both holes are pierced in the same die station from the same flat surface, a competent toolmaker can hold the center distance to about ±0.10 mm. But if the holes were pierced before bending, or the strip is located by the outer contour instead of a pilot pin, 0.3 mm is typical. So your first step is to ask the supplier which die sequence was used and how far the holes are from the bending line. A practical set of production limits for your bracket would be: pierced hole diameter ±0.05 mm, hole-to-hole distance on the same flat surface ±0.10 mm, hole position relative to a formed bend ±0.20 mm, and flatness about 0.1 mm per 25 mm unless a flattening or coining operation is added. Compare your drawing against these numbers before blaming the supplier. Then measure at least 10 to 15 parts from more than one coil or batch. If the 0.3 mm shift always points in the same direction, it is springback and the tooling can be compensated. If it varies from part to part, the process is unstable, and changing the tolerance will not help. Correct the tooling first unless the deviation has no functional effect. For the bow, ask the supplier to add a flattening or coining step, and compensate for bending springback by over-bending the forming stations. For the holes, if they are pierced before forming, ask them to change the sequence to pierce after forming, or switch to a simple progressive die with pilot holes. That alone will normally bring the center distance back to ±0.10 mm. If the shop says it cannot be done on their current tooling, treat that as a signal that the tooling is not suitable for 50,000 pieces per year. Ask for a written correction plan with a deadline. A normal die adjustment for springback and flatness takes two to three weeks, and the next samples should be run from the production die under production parameters, not from a bench tryout. If the assembly can tolerate it, the lowest-risk design change is to turn one of the two round holes into an elongated slot. That removes the springback fighting in that direction entirely and also helps field installation when the wall arm has its own position variance. For the bow, do not judge it from the bare part alone. Assemble the bracket, torque the M6 screws to specification, and measure the residual gap. If the gap disappears under torque and does not affect sealing or durability, the flatness may be cosmetic. But for an outdoor fixture, remember that a visible gap is a water trap, and zinc-plated edges corrode faster than the painted face. If the IP rating or warranty is affected, treat the bow as a functional defect. Before approving the next sample lot, make the supplier prove consistency with a fixture gauge. Send them a go/no-go gauge that simulates the wall arm interface: two locating pins for the M6 holes and a flat reference face for the mounting plane. Require a layout inspection report with measured values from at least five pieces, not just one part. Ask for the material certificate, plating thickness report, and burr direction statement so you can confirm the screw head seats on the burnished side of the hole. Also ask them to describe the measuring method and fixture; a hand caliper across the bracket shell cannot tell you whether the hole pattern is correct relative to the mounting face. If the supplier cannot provide a fixture gauge arrangement, treat that as a red flag; a capable stamping shop will already be thinking in terms of the assembly interface and measurement datums. For future designs, keep these rules in your drawing standard: keep the closest hole edge at least 1.5 times the material thickness plus the bend radius away from a forming line; specify flatness only on functional surfaces and use small embossed pads there instead of expecting the whole face to be flat; avoid putting two precise holes on two different flanges; and use slots wherever one direction of adjustment is acceptable. The 2 mm SPCC and zinc plating are reasonable for a 15 kg static load, but the hole edge quality and plating coverage at the punched edges will determine how that bracket looks after a few seasons outdoors.",
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            "text": "A stamped flat part that bows this way often points to the die design rather than the material. If the blanking station uses excessive cutting clearance or the stripping plate pressure is low, the blank is already bent before it reaches the forming station. Check whether the prototype die has a flattening stage; without one, a 60 mm span on 2 mm SPCC will rarely come out flatter than 0.15 to 0.25 mm. Adding a coining or flattening operation in the last station is a standard fix and does not change the part cost much. On the hole issue, the likely culprit is piloting. If the die locates by the outer contour instead of a pilot pin, every strip width variation directly moves the hole pattern, and the bend operation can shift the formed part relative to the holes. A proper production progressive die should add two pilot holes in the first station and use them to locate the piercing and bending stations; that alone will often bring the center distance from 0.3 mm down to around 0.1 mm. Also check the hole-to-bend distance. If either M6 hole is closer than about 5 mm (1.5 times material thickness plus the bend radius) to the bending line, the material flow during forming will distort the hole edge and its position even if the die position is perfect. In that case the permanent fix is a design change, not a tooling tweak. For a 50,000-piece annual volume, investing in a three-station progressive die with piloting and flattening is justified; accepting a prototype die as the production tool is the real risk here.",
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            "text": "At 50,000 parts per year, the prototype tooling is not the right reference point for your decision. A production die should run with output consistency over long shifts, so the sample approval has to focus on repeatability, not just drawing compliance. Ask the supplier to run 30 to 50 pieces in a row from the production die and record the hole center distance and flatness on every piece. Calculate the Cpk of those two characteristics; a value above 1.33 tells you the process has real capability, while a number below 1.0 means you will see rejects and assembly complaints regardless of what the sample looks like. In early tooling, people often approve based on the best-looking part from a long day of die adjustments, and that is why mass production starts with problems. Also, inspect the burr orientation. For an M6 screw seat, you want the screw head to contact the burnished side of the hole; if the fracture side is on the seating face, the edge will crush under torque and can create an uneven clamping condition. Build a simple inspection fixture that checks hole position with two go pins and flatness with a dial indicator across the mounting face. It takes about 30 seconds per part on the line and protects your receiving inspection from relying on calipers. Finally, consider the plating. Zinc plating after stamping is necessary here, because pre-plated coil leaves raw steel exposed at the punched edges, which is exactly where outdoor corrosion starts. Your supplier should define the plating thickness and add a salt-spray requirement in the purchase specification.",
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            "text": "Before deciding whether 0.2 mm of bow is acceptable, look at the process window behind that number. SPCC coil has a yield strength that can vary by 40 to 60 MPa between coils, and the bending springback follows that variation. If the supplier has not measured the current coil lot against the tooling compensation, the same die can produce different flatness on different production days. Ask them to record the coil number and the rolling direction on the incoming material. When the bend line runs parallel to the rolling direction, springback tends to be larger, and the bow on adjacent flat areas changes as well. Another factor is punch-to-die clearance. For 2 mm SPCC, a practical clearance is roughly 0.15 to 0.20 mm per side, about 8 to 10% of material thickness. If the clearance is too large, the sheared edge has a longer rollover and fracture zone, which weakens the edge around the M6 holes and creates micro-cracks that can propagate under repeated load. If the burr side is not controlled, the holes will measure differently depending on which side you reference, which might explain part of the reported 0.3 mm shift. Also check lubrication: a change in stamping oil changes friction and forming behavior enough to move the bend angle by a few tenths of a degree. The right way forward is to define a process lock: coil spec, lubrication, press speed, and die clearance. When the next sample lot arrives, ask for the process parameters along with the parts, not just the inspection data.",
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            "text": "If the 0.3 mm hole shift is truly a functional problem, stamping may not be the cheapest way to hold that tolerance, and the practical alternatives are worth costing out. A post-stamping machining step can locate the two M6 holes from the mounting face and bring hole position to ±0.05 mm, but adding a drilling or reaming operation on 50,000 parts per year changes the unit cost and adds a fixture alignment error that needs to be managed. A smarter approach is to use a simple jig with a flat reference plate that clamps the stamped bracket, aligns to the same points the wall arm will use, and machines both holes in one pass. That way the tolerance chain runs from the machined holes to the mounting face, bypassing the stamping variation entirely. If the bow itself remains, even machined holes will not make the bracket sit flush. The flat face can be flattened on a press after stamping, but if edge quality matters, a light surface milling pass over the mounting face can achieve 0.05 mm flatness and a uniform sealing surface. That adds cycle time and creates a secondary chip-cleaning issue, so it should be considered only when the bracket carries a gasket or a structural load. Also review the mating arm: the far side of this joint has its own extrusion or machining tolerance. If that side carries ±0.3 mm of position tolerance, your bracket does not need to be perfect because the two-hole fastener pattern has another source of variance anyway. Slotting one hole is usually the lowest-cost way to close that whole tolerance stack.",
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            "text": "Since the bracket only carries about 15 kg static load, the structural risk is low, but the risk of this becoming a field complaint is about the gap and the corrosion path. An outdoor wall-mounted luminaire goes through thermal cycles; the steel bracket and the aluminum housing expand and contract at different rates. If the joint is clamped in a stack where one side is not flat, the preload on the M6 screws will be inconsistent. Over time, one screw may carry more load than the other, and the micro-movement can loosen the joint under wind-induced vibration. The gap also matters for the seal line if there is a gasket between the bracket and the arm. A gasket can usually absorb 0.2 mm of out-of-flatness if it is a closed-cell foam or rubber, but a hard plastic or metal-to-metal interface cannot. Build one complete prototype assembly, torque the screws to the specified value, and then measure the gap with a feeler gauge at four positions around the mounting face. Then remove the bracket and check the screw torque again after a thermal cycle from -20°C to 60°C. That test will tell you whether the bow is a cosmetic nuisance or a long-term loosening risk. Also, do not ignore the edges of the punched holes. The fracture zone of a pierced hole has less plating coverage and can start rust staining on a zinc-plated part within one season of outdoor exposure. Specify deburring and require a salt-spray test on the finished bracket, not just the flat panel sample, because the punched edges are the weakest point.",
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          ,          {
            "@type": "Answer",
            "text": "Set aside the quality debate for a moment and look at the geometry. If two round M6 holes on a mounting face are expected to match a mating arm that has its own tolerance, the drawing is demanding more from a stamped part than necessary. The design should state which surface is the primary datum and which hole is the position reference. Stamping can comfortably hold about ±0.10 mm from one pierced hole to the other hole on the same plane, but once a bend is involved in the tolerance chain, the realistic number expands to ±0.20 to 0.30 mm, and no process volume will magically fix that if the hole sits too close to the bending line. For 2 mm SPCC, keep the distance from the hole edge to the bend radius start at a minimum of 1.5 mm plus the bend radius; in practice, that means at least 5 mm. If the current bracket violates that, a tooling correction will still leave a part that is sensitive to coil thickness variation. Instead, reduce the sensitivity by turning one of the holes into a slot oriented to the direction where field adjustment is acceptable. This is not a relaxation of quality; it is a design decision that recognizes how stamping actually behaves. If the visible gap is the concern, add three small embossed pads around the mounting holes instead of trying to flatten the entire face. The pads can be held flat within 0.05 mm by the die, while the surrounding panel is allowed to bow. Finally, do not put tight positional tolerances on a zinc-plated surface without specifying a measuring datum and a fixture, because plating buildup on edges can measure like a half-tenth of a millimetre of deviation.",
            "upvoteCount": 0,
            "url": "https://www.hyneu.com/questions/stamped-metal-mounting-bracket-tolerances.html#suggestedAnswer-7",
            "datePublished": "2026-10-26T12:57:09Z",
            "author": {"@type": "Person","name": "Claire Ren","url": "https://www.hyneu.com/team/claire-ren.html"}          }
                  ]
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