Last updated: 2026-09-04 · 5 min read
Mold Runoff Video — What Should You Include in the Trial Video, How Do You Film It, and Why Is It a Critical Part of the Mold Acceptance Package?
A mold runoff video is a recorded clip of the mold cycling in the injection molding machine — it shows the mold plate and machine tonnage, the process parameters on screen, continuous cycling for 20+ shots, and close-ups of ejected parts. The video replaces trust with evidence. The video and the CMM report serve different purposes — the video proves the mold runs correctly, the CMM report proves the parts meet tolerances. Both are required.
Key Facts
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Warpage — Part deformation after ejection caused by uneven shrinkage. Amorphous resins warp less (0.4–0.7% shrinkage). Semi-crystalline resins warp more (1.0–2.5% shrinkage). Fix: uniform wall thickness, balanced cooling, optimized gate location, adequate packing pressure. The related guide covers adjacent topics.
What Should the Mold Runoff Video Include?
Four items, each capturing one data point the acceptance package requires:
| Shot | What to Capture | Why It Matters |
|---|---|---|
| Mold identification | Mold plate number, machine tonnage, date, operator name — visible on a label next to the machine | Establishes the mold’s identity — the customer verifies the correct mold is on the correct tonnage machine |
| Parameter screen | Injection pressure, speed, packing pressure, packing time, melt and mold temperature, cycle time — held steady for 10–15 seconds | The customer compares the on-screen parameters against the process sheet; mismatches reveal flow restrictions or inadequate cooling before the mold ships |
| Continuous cycling | 20–50 shots minimum — mold opening, part ejection, mold closing, injection cycle captured on camera | The customer observes cycle smoothness (no sticking, no flash), ejection consistency (no short shots, no missing cavities) and cycle time stability (±0.5 seconds between shots) |
| Ejected parts close-up | 5–10 parts laid on a white background, cavity numbers visible | Visible defect check: flash, short shots, sink marks, burn marks, flow marks, weld lines — traceable to specific cavities in multi-cavity molds |
The parameter screen shot is where most runoff videos fall short. The camera must hold steady long enough for the customer to read every value — not a quick pan across a flickering screen. If the injection pressure on screen is 30% higher than the process sheet, the mold may have a blocked gate. If the cycle time is 20% longer than quoted, the cooling system may be inadequate. The parameter screen is the data the customer must verify before the mold ships.
How Should You Film the Video and What Should the Customer Look For?
Three filming rules, then four acceptance criteria:
- Use a smartphone at 1080p minimum. Professional equipment is not required. A tripod or a brace against the machine keeps the camera steady. Good lighting on the factory floor ensures parts and parameter screens are readable.
- Narrate the video. The operator should state the mold number, machine tonnage, date and any observations out loud. Audio turns the video from a silent clip into a documented trial record.
- Keep the total length to 5–10 minutes. Long enough to capture 20–50 shots of cycling, short enough to review efficiently. For critical molds (high volume, tight tolerance), request a longer runoff: 500–1,000 shots over 30–60 minutes to verify long-term stability.
Four acceptance criteria the customer checks from the video:
| Criterion | What to Look For | Rejection Trigger |
|---|---|---|
| Cycle time stability | Time between shots consistent | Variation >1 second — process not stable, ejection or gate issue |
| Part ejection consistency | Every shot produces a complete part | Missing cavity on any shot — blocked gate or insufficient venting |
| Mold operation smoothness | Open and close without hesitation | Sticking, unusual noise — guide pins, bushings or ejectors misaligned |
| Part quality | Parts free of visible defects | Flash, short shots, sink marks, burn marks — mold requires correction before shipment |
Runner system — The channel network that delivers melt from the machine nozzle to each cavity. Cold runner: solidifies between shots, produces runner waste. Hot runner: stays molten, eliminates runner waste but adds $15k–$40k to mold cost. The related guide covers adjacent topics.
The runoff video and the CMM report are complementary. The video proves the mold runs correctly. The CMM report proves the parts meet drawing tolerances. Neither replaces the other.
Frequently Asked Questions
Should the runoff video be live-streamed or pre-recorded?
Pre-recorded is the standard. The mold maker records and sends the video for review. Live-streaming via video call is an option when the customer wants to witness the trial in real time — the customer can direct the camera, ask the operator to adjust parameters, and observe the mold for a longer period (30–60 minutes).
Live-streaming provides greater confidence — the customer verifies the video is not edited and that the mold runs consistently over a longer period. The cost is minimal: 30 minutes of operator time. If the customer requests it, the mold maker should accommodate.
Is 20 shots enough to verify the mold?
Twenty shots is the minimum — enough to verify consistent cycling and good parts. But 20 shots does not verify long-term performance. The mold may run well for 20 shots and develop sticking, flash or dimensional drift after 100–500 shots.
For critical molds, request 500–1,000 shots (30–60 minutes of continuous running). The longer run verifies the cooling system holds (cycle time does not increase), the ejector system is reliable (no stuck parts), and dimensions are stable — measure 10 parts from the beginning and 10 from the end; they should be within ±0.02mm of each other.
Can the runoff video replace the CMM report?
No — they serve different purposes and both are required. The video verifies cycling behavior, ejection consistency, process parameters and visible part quality. The CMM report verifies internal dimensions, wall thickness and geometric tolerances (flatness, concentricity) — measurements the camera cannot capture.
The CMM report does not show whether the mold cycles smoothly, whether parts eject consistently or whether the process is stable — those require visual observation. Together, the video and the CMM report provide a complete acceptance picture: the mold runs correctly and the parts meet tolerance.
Key Takeaways
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The mold runoff video is the most transparent form of mold acceptance — it replaces trust with evidence.
If the mold maker is confident in the mold, they will provide a comprehensive video without hesitation. If they hesitate or refuse, the customer should insist on a personal visit to witness the trial or decline the mold shipment until the video is provided and reviewed.
Sources
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Sources: Plastics Technology · Plastics Technology Online · Society of Plastics Engineers (SPE) · ThomasNet