Process reference

Sheet metal surface finishing

A finish is more than an abrasive grade. The direction of the grain, the remaining scratches and the way the part is inspected all affect acceptance.

Horizontal lines indicate grain direction.
The diagonal mark represents a deeper scratch.

Schematic illustration. Not to scale; not a machine setting or measured production result.

Define the face the customer will see

Start by identifying the visible face on the drawing. Specify the direction of the finish relative to a fixed feature such as the long edge, then identify areas where contact marks are unacceptable.

Use a retained physical sample when appearance is part of acceptance. View the sample and the production part under the same lighting and orientation. Turning one part through ninety degrees can change its appearance without changing the surface itself.

Each stage inherits the marks left by the previous one

A fine finishing stage does not automatically remove deeper scratches left earlier in production. Examine the incoming face before choosing the final abrasive. Otherwise, a finer texture may be applied over defects that remain visible underneath.

Record the sequence, not just the last tool. Part orientation, abrasive condition, contact and feed speed all belong in the process record. When the visible pattern changes during a batch, compare those inputs before changing the finish specification.

A roughness number needs a measurement method

Ra describes an average of profile deviations; it does not describe every aspect of appearance or every isolated scratch. If the drawing specifies a roughness parameter, record the unit, measurement direction and the measurement/filter settings used under the applicable inspection procedure.

Measurements taken along and across a directional texture are not interchangeable. Keep the measurement method consistent between the approved sample and later parts. A grit number by itself is not a guaranteed Ra value.

Inspect once more after handling

Check for cross-scratches, uneven bands and contact marks, then examine the part again after unloading and stacking. Damage introduced after finishing can be mistaken for a machine problem.

For stainless steel or mixed-material production, consumable selection and cleaning should follow the contamination requirements of the job. A decorative finish alone does not establish hygienic suitability, corrosion resistance or any particular certification.

Machine reference

TFON Surfacer® TF-RF-3013

The TF-RF configuration combines edge rounding with a finishing unit for parts arriving from burr-free cutting. Keep the specified face appearance separate from the edge-profile inspection.

Maximum material width: 1,300 mm
Published conveyor speed: 0.6–4.0 m/min

Published model data. Material, geometry and configuration affect suitability; these values do not guarantee a result or production rate.

View model specifications

Suitable TFON models

Frequently asked questions

Which grit gives which finish?

A grit number alone does not define a finish. The result depends on the condition of the abrasive, contact pressure, feed rate and material. Acceptance is defined by a reference sample or a measured roughness parameter.

Why does grain direction matter?

With a directional grain, the appearance changes when the part orientation changes. If two parts sitting side by side in an assembly have different grain directions, the difference is visible even when the surfaces are identical. Define the direction on the drawing against a fixed reference.

Can stainless steel and carbon steel be processed on the same machine?

The machine can handle both, but the consumables must be kept separate. Iron particles carried over from carbon steel can later cause rust spots on a stainless surface.

Continue reading: Deal with the cut edge before the final finish