This checklist provides procurement managers with a structured method for auditing a sheet metal fabricator. It covers site conditions, quality documentation, and technical verification. It helps buyers identify red flags and confirm supplier reliability before placing orders.
- Verify capability with physical evidence, not just verbal claims about press brake tonnage or laser precision.
- Check quality documentation for consistency between the customer PO and the internal work orders.
- Look for segregation of raw material from finished parts to prevent cross-contamination and mix-ups.
- Assess the supplier's response to non-conforming material and their corrective action process.
- Confirm that the site layout supports the workflow of bending, welding, and finishing without bottlenecks.
Procurement teams often rely on vendor questionnaires and past performance to select sheet metal partners. This approach leaves gaps. A supplier can claim high tonnage and tight tolerances without proof. Auditing a sheet metal fabricator requires moving beyond the brochure and checking the reality of the shop floor.
This guide provides a structured checklist for evaluating a potential supplier. It is designed for buyers who need to verify capabilities, quality systems, and compliance before awarding production contracts. The items are grouped by theme. Each section includes specific questions and red flags to watch for.
How to verify technical capability
Start with the machine tools. Do not accept the nameplate tonnage of a press brake as the maximum forming force. Ask for the actual forming tonnage at the specific bend radius and material thickness you intend to use. The same applies to laser cutters. Verify the maximum sheet size and the actual cutting speed at the thickness of your parts.
Walk the shop floor during the audit. Watch the operator set the bend sequence. Check for tooling wear. A worn die set increases the risk of surface damage and dimensional drift.
| Check Item | What to Look For | Red Flag |
|---|---|---|
| Press Brake Setup | Correct tooling for the material thickness and bend angle | Using a single die set for all thicknesses |
| Laser Cutting | Clean kerf with minimal dross and heat-affected zone | Dross requiring secondary grinding |
| Welding Stations | Proper shielding gas coverage and operator certification | No visible purge or gas flow indicators |
| Measurement Tools | Calipers, micrometers, and height gauges with recent calibration | Tools with expired calibration stickers |
Checklist:
- Request the latest calibration certificates for all in-house measuring instruments.
- Observe a live forming operation on a part similar to your spec.
- Ask the supervisor to explain the bend sequence for a complex bracket.
- Verify the maximum sheet size handled by the laser cutter.
- Check the storage of tooling and ensure it is protected from damage.
What to look for in quality documentation
A supplier with a good quality system generates records that match the customer requirement. Pull a recent work order for a part similar to yours. Trace the document flow.
Start with the customer drawing. Check the revision level. The work order should reference the exact revision. Then look at the cutting sheet. Does it show the correct material grade and heat number? Check the bending setup sheet. It should list the tooling used and the sequence.
If the supplier uses a quality management system, ask to see the control plan for the specific part. It should define the critical dimensions and the inspection method.
Red flags include:
- Work orders that reference an older revision of the drawing.
- Missing heat numbers on raw material logs.
- Generic inspection sheets that do not list the specific dimensions to check.
- Handwritten notes on work orders without a clear signature.
How to assess material handling
Raw material management is often the weakest link in a small or mid-sized fabrication shop. Poor material control leads to wrong grade usage and mix-ups.
Walk the raw material storage area. Check the segregation of materials. Different grades, such as mild steel and stainless steel, should be stored separately. This prevents cross-contamination and incorrect usage.
Check the storage conditions. Sheet metal should be stored flat and protected from moisture. Corrosion on stored stock is a sign of poor storage or excessive lead time.
Checklist:
- Verify the segregation of raw material by grade and finish.
- Check the storage area for moisture and physical damage.
- Ask how raw material is received and inspected.
- Review the records for material traceability from receipt to final part.
- Check the labeling on all raw material bundles.
What to check in the welding area
Welding quality depends on the operator, the equipment, and the environment. A TIG welder and a MIG welder require different setups and certifications.
For a TIG welder, check the power source settings. The amperage and voltage must match the material thickness. Look for the weld bead. It should be uniform and without porosity.
For MIG welding, check the wire feed speed and the gas flow. Porosity in the weld is a common defect. It can lead to fatigue failure.
Check the operator certifications. Ask for the specific qualification records. The certification should match the material and joint type.
Red flags include:
- No visible shielding gas flow during welding.
- Welders operating without current certifications.
- Lack of pre-weld preparation such as cleaning and edge preparation.
- Welds that require excessive grinding to smooth the surface.
How to evaluate finishing and surface treatment
Finishing is often the final barrier between a raw part and a usable component. Check the surface treatment process.
If the parts are powder coated, check the pre-treatment. The parts must be cleaned and etched before coating. Poor pre-treatment leads to coating failure.
If the parts are painted, check the paint thickness. A thick coating can mask dimensional errors. A thin coating may not offer enough protection.
Check the handling of finished parts. They should be protected from scratches. Use of protective films or corner guards is a good sign.
Checklist:
- Verify the pre-treatment process for powder coating or painting.
- Check the thickness of the finish on a sample part.
- Observe the handling of finished parts to prevent damage.
- Ask for the finish specification used in the process.
- Check the storage of finished goods.
How to assess the management and communication
The shop floor is only part of the picture. The management and communication processes determine how well the supplier handles changes and problems.
Ask for the contact person for each order. They should be a single point of contact. This reduces confusion and speed up problem resolution.
Check the communication tools. Do they use a shared project management tool or a standard email format? A lack of clear communication channels can lead to delays.
Ask about their process for handling changes. If a customer requests a change to the drawing, how is it processed? Is there a formal change control process?
Red flags include:
- Multiple points of contact for a single order.
- Lack of a formal change control process.
- Poor response time to emails or calls.
- No clear escalation path for problems.
What to look for in the final inspection
The final inspection is the last check before the part leaves the facility. It should verify all dimensions and surface conditions.
Check the final inspection station. It should have the necessary tools and a reference drawing. The inspector should be trained and independent of the production process.
Ask for the final inspection report. It should list the dimensions checked and the results. Any deviations should be noted and approved.
Checklist:
- Verify the tools used in the final inspection.
- Check the reference drawing used for inspection.
- Ask for the final inspection report for a recent part.
- Observe the final inspection process.
- Check the storage of finished parts after inspection.
A successful audit reveals a supplier that can meet your requirements. It also helps you understand the risks and how to manage them. Use this checklist as a starting point. Adjust it to fit your specific project and industry. The goal is to verify capability and quality before you commit to a long-term partnership.
Frequently asked questions
How long does a standard fabricator site audit take?
A standard audit typically takes one to two days. It covers the shop floor, quality documentation, and management processes.
Do I need to send a representative for the audit?
Yes, it is best to have a representative from your team. They can observe the process and ask specific questions related to your project.
What if the supplier does not have a formal quality management system?
This is a red flag. You can still work with them, but you will need to implement additional checks and inspections on your side.
Can I audit a supplier online?
A virtual audit can be useful for initial screening. However, it cannot replace a physical visit to verify the actual capabilities and conditions.
How often should I audit a supplier?
Audit annually or after any significant change in the supplier's operations. You can also do spot checks for critical parts.
