1. Start with Undercut Location: Four Common Features
- · Sidewall charging ports or harness openings: normally formed by external lateral pull; prefer a slider.
- · Mechanical lock openings and latch windows: high location and shutoff requirements; prefer a slider with a heel block.
- · Internal assembly clips: if located on the B-side and lateral release is under 12 mm, evaluate a lifter.
- · Gasket compression surface: avoid a slider/lifter witness line across the seal. If unavoidable, control the step model to ≤0.03 mm.
External principle reference: Autodesk defines an undercut as a feature that prevents part ejection and lists sliders, lifters, and collapsible cores as possible solutions. Autodesk Moldflow Undercut Result.
2. Six Selection Thresholds
| Input | Slider recommendation | Lifter recommendation | Action beyond threshold |
|---|---|---|---|
| Undercut location | External / near parting line | Internal / B-side | First redesign the part to eliminate the undercut |
| Effective lateral travel | 8–45 mm | 3–12 mm | Increase mold base or use hydraulic/other core pull |
| Mechanism angle | Angle pin 15–25° | Lifter 8–12° | Check side load, galling, and ejection stroke |
| Undercut depth | 2–20 mm | ≤4 mm preferred | Use a slider or split the part if too deep |
| Dimensional model | ±0.05 mm | ±0.10 mm | Use a separate insert for seals/lock openings |
| Target life | 500,000 cycles | 300,000 cycles | Upgrade steel, hardness, guidance, and spares |
3. Battery-Enclosure Constraints
- Sealing: keep the slider witness line ≥3 mm from the gasket compression band; use a witness-step model of ≤0.03 mm.
- Material: PBT+30%GF causes more abrasive wear than ordinary PC/ABS; shorten inspection intervals for slider wear plates and lifter guide surfaces.
- Venting: lock openings and lateral-window ends trap gas easily. Freeze vent depth from resin data and trial results.
- Cooling: large slider inserts consume waterline space. If the local mold-temperature-difference model exceeds 8°C, add copper-alloy inserts or a separate circuit.
- Flame retardancy: verify material rating and wall thickness against final battery-system requirements; mold structure cannot substitute for material compliance.
Design-validation reference: Siemens NX Mold Design supports undercut recognition, complex slider splitting, motion-range analysis, and dynamic interference checking.
| Maintenance item | Slider | Lifter | Decision model |
|---|---|---|---|
| Lubrication / cleaning | 50,000 cycles | 30,000 cycles | Act sooner if glass-fiber dust is found |
| Guide clearance | ≤0.04 mm | ≤0.06 mm | Refit wear plate / guide groove when exceeded |
| Forming-surface step | ≤0.03 mm | ≤0.05 mm | Apply tighter criteria near sealing surfaces |
| Spares | Angle pin + wear plate | Lifter rod + guide block | Stock one set each at initial production |
5. PXID 12-Day Mechanism-Freeze Process
1. Day 1: input 3D data, material, annual volume, target cycles, molding machine, and sealing requirements.
2. Day 2: mark external, internal, and removable undercuts.
3. Day 3: freeze the parting line, retention side, and ejection direction.
4. Days 4–5: calculate travel, angles, side forces, and safety margins.
5. Day 6: review sealing surfaces, lock openings, assembly datums, and witness lines.
6. Day 7: complete mechanism simulation and full-stroke interference checks.
7. Day 8: freeze steel, hardness, wear plates, guide length, and standard components.
8. Day 9: review waterlines, venting, sensors, and maintenance access.
9. Day 10: issue 2D mechanism drawings, BOM, and critical-dimension list.
10. Days 11–12: complete machining review, T0 validation plan, and spare-parts list.
PXID mold development: submit battery-enclosure 3D data and target cycles to receive an undercut analysis, mechanism recommendation, and T0 validation checklist.
6. Nine Values to Record During the T0 Trial
1. Actual slider or lifter lateral travel (mm).
2. Mold-opening, return, and ejection action time (s).
3. Lock-opening, charging-port, or clip dimensions (mm).
4. Witness-line step and flash thickness (mm).
5. Flatness of the gasket compression surface (mm).
6. Sticking events in 100 consecutive cycles.
7. Maximum sliding-surface temperature (°C).
8. Part deformation after ejection (mm).
9. Scuffing grade on the angle pin, wear plate, or lifter head.
FAQ
Not necessarily. First see whether the undercut can be eliminated by changing the parting line, using a through-feature, or changing assembly direction. If a closed lateral contour is required and pull is perpendicular to mold opening, prefer a slider.
It may reduce mold size and separate slider parts for short internal undercuts, but adds ejector synchronization, guide wear, and maintenance. Compare mold cost, cycle time, and 300,000-cycle downtime—not only initial price.
Yes theoretically, but side force, guide wear, and galling risk rise. PXID recommends 8–12°; above 12° requires a dedicated check, and above 15° normally warrants comparing a slider.
It can be evaluated, but shutoff, wear, and assembly datums also matter. A separate slider or replaceable insert is normally easier to correct and maintain.
Yes. Glass fiber increases abrasive wear. Freeze steel, hardness, surface treatment, lubrication, and spares together.
After receiving 3D data, material, target cycles, annual volume, and sealing requirements, PXID can issue a missing-input list within 24 hours and use the 12-working-day model to freeze mechanism inputs and the T0 plan.
Contact PXID: send battery-enclosure 3D data and target cycles to receive the MOLD-01 slider/lifter selection checklist.Contact PXID
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