To specify abrasive blasting for sheet metal parts, define the desired surface condition, the areas to be treated or masked, the abrasive or acceptable media range, and any limits on distortion, contamination, or surface profile. Include the part material and thickness, the coating or finishing process that follows, and how the result will be inspected. Avoid relying on “blast clean” alone: suppliers need measurable acceptance criteria or a clearly approved visual reference. At Jinhui, we recommend sharing the drawing, material details, and end-use requirements before requesting a quotation so the blasting process can be assessed alongside the part geometry.
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Abrasive blasting propels abrasive media toward a surface to remove contaminants, change the surface texture, or prepare the part for a subsequent finish. The result depends on the substrate, media type and condition, equipment settings, nozzle distance, and operator technique. Blasting is not a single finish grade, so two parts described with the same general term may have different cleanliness and texture. A useful specification describes what the surface must achieve and what defects or changes are unacceptable.
For coating preparation, the goal may be to remove scale or residues and create a suitable texture for paint or another coating. For cosmetic parts, a more uniform matte appearance may matter more than a particular profile value. For deburring or edge conditioning, specify which edges are included and how much edge change is acceptable. Confirm that blasting is appropriate for the material and end use, especially where thin sheet, tight tolerances, or visible faces are involved.
List the material grade when known, sheet thickness, part dimensions, and any relevant surface condition, such as mill finish, laser-cut edges, oil, or existing coating. Include the drawing revision and identify whether the part is supplied flat, formed, welded, or assembled. Geometry can affect access and consistency: narrow recesses, folds, and internal corners may not receive the same exposure as open faces. If material details are uncertain, state that clearly and ask the supplier to review them before processing.
For example, a request might identify a carbon-steel panel with a nominal thickness of 1.0 mm. This is an illustrative specification detail, not a recommended minimum thickness for blasting. The supplier should assess the actual part geometry, material, and process risk rather than assume that a single thickness value guarantees a distortion-free result.
Mark the required surfaces on the drawing or provide a clear annotated image. Identify areas to mask, including threads, precision fits, electrical contact points, labels, seals, and surfaces that must retain their existing finish. State whether both sides, cut edges, welds, or formed features are included. If a keep-out region is important, dimension it from a recognizable datum rather than describing it only as “near the hole.”
As an illustrative drawing callout, a buyer might define a 5 mm masked zone around a specified feature. The appropriate distance depends on the part and functional requirement, so confirm it with the supplier. Also explain whether masking residue is acceptable and how the protected area will be checked after processing.
Cleanliness and surface profile are different requirements. Cleanliness describes the removal of unwanted material, while profile describes the texture created by blasting; one does not automatically define the other. State the required cleanliness method or visual reference where it is important, and define a profile range only when the downstream coating or engineering requirement calls for one. If your coating supplier has a preparation requirement, include that document or its relevant acceptance criteria in the inquiry.
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For instance, a drawing may use an illustrative profile target of Ra 3.2 μm, subject to confirmation that this parameter and value are appropriate for the coating system and measurement method. Ra is not interchangeable with every surface-profile metric, and a roughness measurement may not fully describe a blasted surface. Agree on the parameter, sampling location, and inspection approach before production.
For visible parts, provide an approved sample or reference image that shows the acceptable texture and uniformity under agreed viewing conditions. Specify whether color variation, directional marks, edge contrast, or minor visual variation can be accepted. Identify dimensions, flatness, and fit features that must remain within drawing tolerances after blasting. Do not assume that blasting will leave every dimension and edge unchanged; discuss sensitive areas with the supplier in advance.
Thin panels and parts with large unsupported spans deserve particular attention because process impact and handling can affect flatness. Ask the supplier to review whether a process trial, adjusted exposure, fixturing, or a different finishing method is advisable. If distortion is a critical risk, define how flatness will be measured and at what stage of processing. Avoid inventing a tolerance that is not supported by the product’s functional requirements.
If your engineering team requires a particular abrasive, specify it and explain why, such as a coating requirement or contamination restriction. Otherwise, state the functional result and ask the supplier to recommend suitable media for the substrate and finish. Media options can differ in hardness, shape, recyclability, and the texture they produce, so a material name alone does not guarantee a consistent result. Ask how the supplier will control media condition and prevent unwanted residue or cross-contamination when these issues matter.
Also identify any restrictions on chemicals, residue, or subsequent cleaning, and state whether parts need to be dry, protected, or packaged for the next operation. If blasting is followed by painting, plating, bonding, or another surface treatment, specify the sequence and any handling limits between steps. The appropriate requirements depend on the full process chain, not only the blasting operation.
Send the supplier the latest drawing, material and thickness information, annual or batch quantity, required finish, and any downstream coating requirements. Include photographs or a physical reference when appearance is subjective, and mark treated and masked regions directly on the drawing. Ask the supplier to identify assumptions, proposed inspection methods, risks to thin or precision features, and any additional setup or sample-approval steps. This makes the quotation easier to compare because suppliers are responding to the same scope.
Before approving production, agree how first-off parts will be reviewed and what constitutes acceptance. For repeat orders, keep the approved sample, specification revision, and inspection notes linked to the part number. If the process or material changes, review whether the original requirements still apply. These controls help reduce interpretation differences without promising that every geometry will behave identically.
The clearest way to specify abrasive blasting for sheet metal parts is to define the material and geometry, identify treated and protected areas, state the required cleanliness and texture, and explain how appearance and dimensions will be accepted. Add measurable limits only when they are relevant and use an agreed measurement method; otherwise, provide an approved visual reference and invite a technical review. Before placing an order, ask the supplier to confirm process suitability for thin sections and any risks to flatness, edges, or functional features. Contact Jinhui with your drawing and finishing requirements to discuss the scope, clarify assumptions, and prepare a suitable quotation.
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