Issue: Poor Class-A Appearance
Visible weld features do not conform to the requirements of the applicable standard.
Same as: Poor Class I or cosmetic weld appearance.
Description
Spot welds are typically classified both in terms of their functional requirements and their surface appearance. The most stringent cosmetic stipulation is for the appearance of a surface (usually customer-visible) to be free from markings or imperfections such that a weld is not visible after painting.
Other requirements may limit the displacement, indentation, or distortion of the parent metal. These criteria are normally specified as a percentage of the governing metal thickness. Weld flash may also be specified as unacceptable.
Detection
Detection is normally by visual inspection of the weld surface. Measurements may be required on marginal indentation or displacement calls.
Significance
Quality, Workplace Issues, Cost, Downtime, Maintenance, Throughput (cycle time; PPH), are all potentially affected by this condition. Special considerations are noted below:
Quality: Welds not satisfying the appearance requirement may adversely affect the
function of seals, fit of trim, customer quality perception etc.
Possible Causes
Strong Possibilities
- Damaged part
- Dirty material
- Electrode faces not parallel to workpiece
- Hold time short
- Inadequate electrode alignment
- Inadequate or no gun equalization
- Incorrect cylinder
- Incorrect electrode dressing
- Poor electrode follow-up
- Poor or varying part fit-up
- Poor weld accessibility
- Shunting of guns or parts
- Weld current high
- Weld force high
- Welds wrongly located
Weak Possibilities
