Sourcing Sheet Metal Parts: Quality Details Beyond the Unit Price
How bend angles, hole locations, deburring, packaging and reverse engineering connect sheet metal sourcing with reliable inspection and assembly.
In our sourcing and manufacturing experience, sheet metal parts are a product category worth evaluating for production in Asia. Material procurement and bending can offer competitive costs when the material, order quantity and part requirements are a good fit.
Some combinations of production origin and import market may also offer more favorable customs duties. That needs to be checked against the product's tariff classification, country of origin and destination; manufacturing in Asia alone does not establish a duty advantage. In the EU, for example, preferential tariffs depend on applicable trade arrangements and origin requirements. The actual duties must be checked for the specific product and market. European Commission Access2Markets: Basic customs duties
For us, the aim of sourcing sheet metal parts is to carry the cost advantage through to receipt and assembly at the customer's site. Finding a lower factory price is only one part of that work.
When comparing quotations, we therefore consider inspection, packaging, freight and potential rework alongside material and fabrication costs.
Work Back from Assembly to Define Bend Angles and Hole Locations
Sheet metal fabrication may appear to be a straightforward sequence of cutting, making holes and forming a few bends. Controlling dimensions and hole alignment after forming takes more planning than the flat drawing may suggest, particularly when dimensions span several bends. Protolabs: Sheet metal design guidelines
Before placing an order, we first clarify which angles affect installation, which holes must align with mating parts, and whether the functional requirement concerns an individual dimension or the relative position of features in the assembled product.
Consider a bracket with mounting holes on both sides. Correct hole spacing in the flat blank does not by itself establish that the formed bracket will fit. The distance between holes and bend lines, and the resulting geometry after forming, also need review. Holes close to a bend may distort as the material stretches during forming. Protolabs: Feature proximity to bends
We recommend defining critical angle tolerances, hole-location datums and assembly relationships in the sourcing documents. Where necessary, use a first-article fit check or an agreed checking fixture rather than relying only on flat-pattern dimensions.
Not every dimension needs a tight tolerance. Features that affect function and assembly do need to be correctly defined, made and verified.
Define Deburring Beyond a General Edge-Finishing Note
Hole edges and the outer profile deserve the same attention as angles and hole locations. Burr removal, edge rounding and surface grinding are separate operations that can be specified individually. Equipment manufacturer Hans WEBER also identifies them as distinct processing functions. Hans WEBER: TTSC processing functions
We encourage customers to identify whether hole edges need treatment on both sides, which edges people will handle, and which edges will contact cables or other components. Any required chamfer or edge radius should also be stated.
After deburring, critical hole diameters, mating features and appearance still need to meet the drawing requirements. A useful sourcing document defines the treatment area and acceptance method as well as requiring burr removal.
Agree Packaging and Support During Sourcing
We treat delivery as more than the completion of fabrication. Loading and securing belong in the delivery plan as well. The IMO/ILO/UNECE CTU Code provides guidance on loading and securing cargo transport units for sea and land transport. It is a useful reference for transport planning; the packaging for an individual part still needs to suit its structure and shipping method. IMO: CTU Code
For sheet metal parts, we discuss separation between parts to prevent rubbing, protection for projecting formed features, and the locations that can safely carry a load. We also examine whether stacking loads will be carried by the packaging structure or transferred directly into the parts.
Large or thin parts, and parts with projecting flanges, need particular attention to support and restraint. Adding more cushioning alone does not establish an adequate packaging design. The load path and protection arrangement need to make sense for the part.
Before production, we recommend agreeing the packaging format, quantity per carton, orientation and any necessary support structure. Photos or a packaging specification then provide a reference for subsequent batches.
Passing inspection before shipment is one step. Our delivery objective is for the customer to unpack parts that are still ready to use.
Start with Reverse Engineering When Only a Sample Is Available
Reverse engineering is another starting point customers can discuss with us. Based on the existing part and available information, we can help define and coordinate the scope of measurement, modeling, drawing preparation and verification.
When a customer has only an existing part or incomplete drawings, physical measurement, supplemented by 3D scanning where appropriate, can provide geometry for reconstructing a CAD model. Converting scanned point clouds or meshes into usable CAD models is one practical application of reverse engineering. ZEISS: Reverse engineering
For us, the purpose of reverse engineering is to build information that supports repeatable manufacturing, inspection and assembly, beyond reproducing the sample's visible shape.
Alongside geometry, we work with the customer to clarify material, sheet thickness, critical dimensions, angle tolerances and mating relationships. If a sample is worn or may have deformed, its measured shape needs to be distinguished from its intended function. The resulting drawing should be confirmed by the customer and verified through samples and trial assembly.
Low-Cost Parts Can Still Make an Important Difference
We do not treat a sheet metal part as a price-comparison exercise simply because its unit value is low.
The practical goal is to manage angles, hole locations, edges, inspection and packaging at a reasonable cost, so the customer does not have to spend time reworking parts, adjusting assemblies or rescheduling production after receipt.
That is the value we aim to provide: starting with drawings or samples, connecting manufacturing requirements with assembly and delivery needs, and coordinating suitable fabrication and inspection work.
Good sheet metal sourcing means making the right part at a reasonable cost and preserving its condition through delivery.
For a quotation, provide a drawing with its revision or information about the existing sample, material grade and sheet thickness, quantity, critical angles and hole locations, finish, destination and packaging requirements. Review our sheet metal fabrication service, then request a sheet metal quotation so we can confirm the production scope and acceptance requirements.