Burr Direction on Stamped Parts: Put the Functional Edge on the Drawing

Identify which edge matters

A stamped edge can affect handling, assembly, coating and contact with a neighboring component. Mark the regions that touch a seal, cable, sliding surface or user-accessible area. The required control should follow that function. A blanket burr note can either miss a critical orientation or impose unnecessary work on edges that have no comparable requirement.

Separate direction from size

The side on which a burr appears and the amount of burr are different characteristics. Define the required orientation using an unambiguous drawing view or identified face. Where necessary, state a measurable limit and inspection method. Avoid subjective requirements such as “small burr” because different inspectors may accept different edge conditions while believing they are following the same drawing.

Review tooling and forming sequence

Blanking direction, tooling condition and subsequent forming can affect where the finished edge is presented to the assembly. Discuss the process sequence with the stamping supplier before freezing orientation-sensitive features. A part that is flipped during a later operation can place the burr on the wrong functional side. Ensure the work instruction and fixture prevent that reversal or provide a reliable check.

Validate any secondary edge treatment

Brushing, tumbling or another finishing operation can change dimensions, corner condition and appearance as well as the burr. Confirm that the selected route reaches the critical edge without damaging thin tabs or decorative surfaces. Inspect after the last operation that can alter the edge. If the part is coated, determine whether coating hides the defect visually without removing its functional effect.

Connect wear checks to the edge requirement

Tool wear can change edge quality over a run. Include suitable setup and production checks in the control plan, with a reaction rule for approaching or exceeding the specified limit. Keep samples or images when they improve consistent interpretation. If a mating component is damaged in assembly, examine the edge orientation and actual contact path as well as the measured burr size.

Approval checklist and evidence

Worked review example

Illustrative scenario: a stamped bracket meets its outline dimensions but scratches a cable jacket because the burr faces the cable route. The drawing previously controlled only overall size. The revision identifies the cable-contact edge, specifies its accepted condition and fixes the orientation in the manufacturing and assembly instructions. The supplier validates the treatment on that edge rather than applying a cosmetic finish to the broad faces alone.

Information for the engineering review

• Functional edge and contact path
• Identified burr side
• Measurable edge requirement
• Forming and finishing sequence
• Tool-wear checks and reaction rule

Discuss this requirement with KEC Tour using the controlled drawing, the relevant mating interfaces and the review information above. Identify the decision that needs confirmation and the acceptance evidence expected with the first parts.

Sources and further reading

• ASME drawing and tolerancing standards
• ISO quality management

Frequently asked questions