Resistance spot welding — typical applications and thickness range Spot welding is primarily used to join overlapping sheet-metal parts (lap joints) within a practical thickness range. Choose the most appropriate statement.

Introduction / Context:
Resistance spot welding creates localized fusion between overlapping sheets by passing high current through electrodes under pressure. It is a cornerstone of automotive body-in-white assembly and appliance fabrication.

Given Data / Assumptions:

• Standard single-spot weld with copper alloy electrodes.
• Mild steel or stainless steel sheets typical of automotive and appliance applications.
• No special multi-pulse or projection arrangements unless stated.

Concept / Approach:
Spot welding forms a nugget between overlapped sheets (lap joint). The feasible thickness range per sheet is commonly about 0.5 mm to 3 mm using standard machines. Greater thicknesses require very high currents, larger electrodes, or alternative processes such as seam welding or arc welding.

Step-by-Step Solution:
Identify joint type: lap joint for overlapping sheets.Recall typical practical sheet thickness range per sheet ≈ 0.5–3 mm.Therefore, select the statement reflecting lap joints in this range.

Verification / Alternative check:
OEM weld schedules specify current, time, and force for common gauges in the 0.5–3 mm range; beyond this, multi-spot or alternative processes are favored.

Why Other Options Are Wrong:
Very thick lap joints (option b) exceed normal single-spot capability; butt joints (options c and d) are not standard for spot welding since nuggets require overlap; option e is contrary to the fundamental lap-joint nature of spot welding.

Common Pitfalls:
Poor electrode tip maintenance leading to expulsion; inadequate clamping force causing weak nuggets; ignoring surface coatings (e.g., galvanizing) that demand adjusted parameters.

Final Answer:
Used for lap joints in sheets of about 0.5 mm to 3 mm thickness