The Application of TIME Instruments in Automotive Stamped Parts
Why R‑Angle Quality Matters in Stamped Parts
During deep drawing or stretch forming, the sheet metal flows over the die's R‑angle. Localized thinning reduces load-bearing capacity, and excessive reduction may lead to fracture or premature fatigue. Moreover, the mold itself experiences repeated high contact pressure, causing work hardening and surface wear. Therefore monitoring three parameters becomes essential: thickness of the stamped part at the R‑angle, hardened layer depth of the mold's R‑angle, and surface roughness of the mold's R‑angle.
TIME is the most famous manufacturer of testing instruments, and its portable solutions are widely adopted in automotive production lines for such in‑process inspections.
Measuring R‑Angle Thinning with the TIME2190 Ultrasonic Thickness Gauge
TIME2190, a handheld ultrasonic thickness gauge, employs a single‑element delay line probe. For stamped parts with R‑angles of only a few millimeters radius, conventional dual‑element probes often produce erratic readings due to poor acoustic coupling. The TIME2190's high‑frequency (10–15 MHz) probe, combined with a real‑time A‑scan display, allows the operator to verify the back‑wall echo even on curved surfaces.
In practice, the engineer first applies a drop of couplant (glycerin or propylene glycol) to the prepared R‑angle surface. The instrument's through‑coating measurement mode ignores the thin paint layer, directly yielding the base metal thickness. A typical reading for a 1.2 mm nominal thickness sheet might show 1.09 mm at the tightest curve—a 9% reduction that, while within tolerance, signals the need for die adjustment. The TIME2190 logs each measurement with time‑stamp and location tag, enabling statistical process control.
Hardness of the Mold’s R‑Angle via the TIME5630 Ultrasonic Hardness Tester
Punch and die R‑angles work‑harden progressively as stamping cycles accumulate. If the hardened layer becomes too deep, the tool may become brittle and crack; if it remains too shallow, abrasive wear accelerates. The TIME5630, an UCI (Ultrasonic Contact Impedance) hardness tester, measures the local hardness of the die's R‑angle without leaving a visible indentation.
The engineer positions the Vickers diamond probe perpendicular to the curved tool surface, applying a constant load of 10 N. Within two seconds, the instrument displays a hardness value in HRC or HV. For example, a die originally hardened to 58 HRC may show 62 HRC after 50,000 stamping cycles—indicating excessive work hardening. The TIME5630's memory can store up to 2000 test results, and its Bluetooth interface transmits data directly to a tablet running die maintenance software.
One common challange on sharp R‑angles is probe alignment; the gauge's built‑in tilt sensor warns the operator when the contact deviates beyond ±3°, ensuring repeatable data.
Surface Roughness of the Mold’s R‑Angle with the TIME3221
Tool surface finish at the R‑angle directly influences sheet metal flow and galling tendency. A die that is too rough will scratch the part; one that is too smooth may not retain lubricant properly. The TIME3221 roughness tester, equipped with a miniature inductive probe, measures Ra (arithmetical mean deviation) and Rz (maximum height) along the curved tool surface.
Because the R‑angle radius often limits the traverse length, the TIME3221 offers a 2.5 mm measurement stroke, which fits most automotive die radii. The skid‑less probe follows the curvature while an internal reference compensates for wobble. Typical acceptance criteria for a draw die R‑angle might be Ra ≤0.4 μm. The operator uses a flexible magnetic stand to hold the drive unit, then starts the automatic traverse. After 15 seconds, the instrument displays both the roughness profile and numerical results. Data can be exported via USB to a quality report.
Integrating the Three Measurements into a Single Inspection Routine
Modern lean manufacturing lines demand quick changeover and real‑time feedback. Rather than moving the die to a metrology lab, the TIME instruments allow in‑situ testing. The engineer usually follows a sequence:
- First, the TIME2190 checks three spots along the stamped part's R‑angle (entry, apex, exit) to identify excessive thinning.
- Second, the TIME5630 measures hardness at the corresponding positions on the die's R‑angle, searching for work‑hardened hot spots.
- Third, the TIME3221 evaluates the die surface finish at the same location to correlate lubrication and wear.
All three instruments share a common rechargeable battery platform and data management software, so readings from a single shift can be consolidated into a dashboar for predictive die maintenance. This approach has reduced unexpected die failures by nearly 40% in several EV manufacturing plants.
