{"id":11162,"date":"2026-01-22T22:15:00","date_gmt":"2026-01-22T14:15:00","guid":{"rendered":"https:\/\/dewintech.com\/blog\/when-purchasing-welding-parts-how-should-i-communicate-with-suppliers-regarding-acceptance-criteria-for-cosmetic-defects-such-as-scratches\/"},"modified":"2026-01-22T22:15:00","modified_gmt":"2026-01-22T14:15:00","slug":"al-comprar-piezas-de-soldadura-como-debo-comunicarme-con-los-proveedores-con-respecto-a-los-criterios-de-aceptacion-para-defectos-cosmeticos-como-rayaduras","status":"publish","type":"post","link":"https:\/\/dewintech.com\/es\/blog\/when-purchasing-welding-parts-how-should-i-communicate-with-suppliers-regarding-acceptance-criteria-for-cosmetic-defects-such-as-scratches\/","title":{"rendered":"Al comprar piezas de soldadura, \u00bfc\u00f3mo debo comunicarme con los proveedores sobre los criterios de aceptaci\u00f3n de defectos cosm\u00e9ticos (como ara\u00f1azos)?"},"content":{"rendered":"

\n \"Inspecting\n<\/p>\n

We often see perfectly welded silver aluminum frames get rejected silver aluminum frames<\/a> 1<\/a><\/sup> simply because the surface finish expectations were not clearly defined during the initial quoting phase.<\/p>\n

Communicate cosmetic acceptance criteria by embedding specific visual standards directly into your technical drawings and purchase orders. You must define allowable scratch depth, location zones, and viewing conditions. Providing physical limit samples and requiring First Article Inspection Reports ensures alignment and prevents costly disputes over subjective quality issues.<\/strong><\/p>\n

Let's break down the exact steps to ensure your suppliers understand your visual expectations.<\/p>\n

What details should I include in my technical drawings to define visual acceptance standards for welded components?<\/h2>\n

Our engineering team consistently finds that vague notes like "clean finish" lead to inconsistent results and unnecessary friction on our production lines in Vietnam.<\/p>\n

Your technical drawings should explicitly classify surface zones based on visibility, separating customer-facing areas from internal components. Include quantitative metrics for maximum scratch length, depth, and density per square inch. Reference industry standards like ISO 5817 while adding specific notes for aesthetic requirements to remove ambiguity.<\/strong><\/p>\n

![Engineer reviewing technical drawing on computer (ID#2)](https:\/\/dewintech.com\/wp-content\/uploads\/2026\/01\/v2-article<\/a> First Article Inspection<\/a> 2<\/a><\/sup>-1769090977242-2.jpg "Technical drawing review")<\/p>\n

When we develop custom aluminum frames, relying solely on structural welding codes structural welding codes<\/a> 3<\/a><\/sup> is never enough structural welding codes<\/a> 4<\/a><\/sup> for the final look. Standard welding codes focus on strength, not beauty. To bridge this gap, you must treat your technical drawing as a contract for appearance, not just dimensions.<\/p>\n

Establish Visual Zones<\/h3>\n

The most effective method we use is "Zoning." You cannot expect a Class A surface finish on the underside Class A surface finish<\/a> 5<\/a><\/sup> of a machine base. On your drawings, color-code or hatch specific areas of the part to indicate their visibility level. For a silver-colored lattice frame, scratches on the outer vertical supports are glaringly obvious, while marks on the inner connecting joints might be acceptable.<\/p>\n\n\n\n\n\n\n\n
Zone Classification<\/th>\nDefinition<\/th>\nAcceptance Criteria<\/th>\n<\/tr>\n<\/thead>\n
Zone A (Primary)<\/strong><\/td>\nSurfaces directly visible to the end-user during normal operation.<\/td>\nZero scratches visible from 600mm distance. No discoloration or pits.<\/td>\n<\/tr>\n
Zone B (Secondary)<\/strong><\/td>\nSurfaces visible only when covers are removed or during maintenance.<\/td>\nMinor scratches <5mm length allowed. Max 2 defects per surface area.<\/td>\n<\/tr>\n
Zone C (Internal)<\/strong><\/td>\nNon-visible structural components.<\/td>\nStandard structural weld quality. Cosmetic scratches accepted if coating is intact.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Quantify the Unquantifiable<\/h3>\n

Avoid subjective terms like "free from defects." Instead, use numbers. In our experience sourcing for US clients, we specify that for Zone A surfaces, no scratch shall exceed 0.05mm in depth. We often require a "fingernail test"\u2014if a fingernail catches on the scratch, it is too deep for painting painting or anodizing<\/a> 6<\/a><\/sup> or anodizing to hide. By putting these specific numbers in the drawing notes, you give the quality control team a clear pass\/fail standard.<\/p>\n

Do I need to provide physical limit samples to establish clear boundaries for surface scratches and finish?<\/h2>\n

We have avoided countless arguments by sending physical "Golden Samples" to our workshops before mass production begins to set the standard.<\/p>\n

Yes, providing physical limit samples is essential for subjective cosmetic criteria where photographs fail to capture depth or texture. Create a "limit sample" library showing the maximum allowable scratches and finish variations. These samples serve as the ultimate benchmark for quality control inspectors when drawings are open to interpretation.<\/strong><\/p>\n

\"Person<\/p>\n

Photographs are notoriously deceptive. A flash can wash out a scratch, or a shadow can make a minor imperfection look like a crack. This is particularly true for metallic, reflective surfaces like silver aluminum extrusions aluminum extrusions<\/a> 7<\/a><\/sup>. When we manage projects involving aesthetic parts, we rely on physical references to align our eyes with the factory's eyes.<\/p>\n

The Power of the Limit Sample<\/h3>\n

A "Golden Sample" usually represents a perfect part, but a "Limit Sample" is often more valuable. This is a physical part that represents the worst<\/em> condition you are willing to accept. We often take a rejected part, mark the specific defects that pushed it over the edge, and send it to the supplier. They hang this on the QC wall. If an inspector is unsure about a scratch, they can physically compare it to the limit sample.<\/p>\n

Managing the Sample Library<\/h3>\n

You need a system to track these samples. We recommend signing and dating two identical sets of samples\u2014one for you and one for the supplier. This prevents the "bait and switch" scenario where standards drift over time.<\/p>\n\n\n\n\n\n\n\n
Sample Type<\/th>\nPurpose<\/th>\nWhen to Use<\/th>\n<\/tr>\n<\/thead>\n
Golden Sample<\/strong><\/td>\nShows the ideal target finish.<\/td>\nUse for sales references and final assembly alignment.<\/td>\n<\/tr>\n
Boundary Sample<\/strong><\/td>\nShows the maximum acceptable defect level.<\/td>\nUse on the production line for daily Go\/No-Go decisions.<\/td>\n<\/tr>\n
Defect Sample<\/strong><\/td>\nShows specific unacceptable defects (e.g., weld spatter).<\/td>\nUse for training new welders on what to avoid.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

This physical alignment reduces the "I thought it looked okay" excuse. It turns a subjective opinion into an objective comparison.<\/p>\n

How can I structure my QC inspection checklist to ensure cosmetic defects are identified before shipment?<\/h2>\n

Our quality managers in China strictly enforce standardized inspection checklists to catch surface imperfections before products are crated and shipped.<\/p>\n

Structure your QC checklist to include specific inspection parameters such as lighting intensity, viewing distance, and viewing angle. Require inspectors to document cosmetic compliance using a "pass\/fail" matrix based on your pre-defined zones. Mandate the inclusion of high-resolution photos in the final inspection report to prove the surface condition prior to shipment.<\/strong><\/p>\n

\"Blueprint<\/p>\n

A checklist is only as good as the environment in which it is used. If an inspector checks a silver frame in a dimly lit warehouse, they will miss fine scratches that your customer will see immediately under retail lighting.<\/p>\n

Standardize Inspection Conditions<\/h3>\n

We define the "viewing conditions" explicitly in our checklists. For cosmetic parts, we require specific lighting intensity (usually 1000+ Lux) lighting intensity<\/a> 8<\/a><\/sup> lighting intensity<\/a> 9<\/a><\/sup> and a specific viewing distance (typically 18-24 inches). We also specify the viewing time. A quick glance isn't enough, but examining a single bracket for 10 minutes is inefficient.<\/p>\n

The Checklist Anatomy<\/h3>\n

Your checklist needs to be granular. Don't just ask "Is the finish good?" Break it down by defect type and location.<\/p>\n