詳細／分析

Custom Silicone Cover Defects: Why Do the Spray and the Print Keep Failing? The customer sent the samples back. Missing spray. Broken silkscreen. You change the air pressure and the nozzle. The defects stay. Missing spray is usually a fixture that blocks the groove shadow, or mold release left on the part. Broken silkscreen is usually shrinkage under the mesh. Fix the fixture and the mesh, not the pressure. I have collected many reports like this over the years. Nobody cares at the sample stage. At mass production it becomes a full lot return. So let me take this case apart, from the fixture and the mold release, to shrinkage, […]

Silicone Grommet Ring at 80% Flash: What Went Wrong? Our sample run of a silicone grommet ring came back with 80% flash. The customer was waiting. Two causes. The mold plates did not close tight, so flash grew thick. Trimming was rushed, so burrs stayed. A few days ago, the customer sent me the sample photos. The red box marked the problem area. The burrs were very clear. The edge was uneven. I looked at those photos for a long time, and I did not feel good, because the problem came from us. I will tell the story in order. From the complaint, to the cause, to the new sample, […]

Are the Colored Specks on Your Silicone Roller Really Dirty Compound? 12,000 pcs shipped. 315 pcs sampled, a 2.25% reject rate. Three defects, all from the bench. The compound was clean. Leftover material from the previous run stuck to the new parts. The bulge and the shiny marks came from handling too. The customer sent a quality improvement notice. They wanted the cause by September 22 and visible improvement by September 25. The clock was tight. The investigation was not long. Why Does Leftover Compound End Up on the New Part? 315 pcs sampled, a 2.25% reject rate. The specks the customer circled had the wrong color, and they sat […]

Why Does a Silicone Grommet Ring 0.115 mm Undersize Fall Out? 90,000 pcs shipped. The customer returned 56 pcs. We measured an OK sample, and the size was fine. We measured the wrong thing. The sealed sample was fine. The 56 returns were not. Their OD ran 23.885 mm, which is 0.115 mm below the lower limit. I still remember both numbers from this one: Ø24 +0.1/-0 and 1.0 +0.05/-0. Both fell below the bottom of the band. One missed by 0.115 mm, the other by 0.018 mm. Here is the order we worked through it. Why Did We Pass the Part and the Customer Fail It? The customer said […]

Why Does the Silicone Extrusion Process Fail Length Tolerance? A complaint came in: the strips were out of tolerance. The machine was fine. The problem sat at the cutting table. Most length failures are not the fault of the silicone extrusion process. They come from four details: cutting timing, cutting force, packaging, and measurement method. This complaint looked small. It hid four traps. I will open each trap one by one. You can check your own workshop as you read. The first trap came early, and most people miss it. Why Can’t You Cut Silicone Strips Right After Vulcanization? An operator cuts the strip the moment it leaves the die. […]

Why Does a Silicone Compression Molding Machine Make Uneven Flash? Parts from the same cycle came back. Excess rubber squeezed out at the parting line is called flash. On this lot, the excess was paper thin on the left edge and thick enough to need a knife on the right. Inspection rejected the batch. A silicone compression molding machine pushes excess rubber to one side when the base plate is not flat or the guide pins are worn. The two mold faces stop being parallel. At first I blamed the silicone weight and the vents. The real problem was the plate under the mold, the one nobody looks at. Why […]

Why Do Custom Silicone Gaskets Deform in Bulk? Two hundred custom silicone gaskets came back. Sixty-three were deformed. The box carried an urgent handling tag. Stress in a square ring is uneven. If the part cools without setting, it twists on its own. Stacking pressure is only the last straw. We inspected every piece and remade the lot. Then we went back to the cause. What we found sat deeper than the report. Parts from the same mold should share one shape. These sixty-three did not, and each one started to move at a corner. The four corners carry stress in different directions. The part was still hot when it […]

Why Do Custom Silicone Rubber Plugs Come Out Small and Soft? A customer returned a batch of custom made silicone plugs. They were 0.37 mm short and too soft. Small size and low hardness are two symptoms of one cause: under-cure. The parts demolded before they set and froze at the wrong size. I did not let the customer absorb this. We inspected the stock, recalled the shipped lot, and paid the freight. Then we looked for the cause. Why Do Small Size and Low Hardness Always Appear Together? The customer saw two problems. Small, and soft. We saw one clue. Under-cure lowers crosslink density, so hardness drops. It also […]

Why Do Visually Flawless Silicone Parts Develop Internal Voids and Under-Curing? Custom silicone rubber parts can look perfect outside but hide uncured soft cores within. Overlooking internal voids results in catastrophic assembly failures. I share our root cause case review to protect your production line. Silicone products develop internal voids and softness when molding temperatures stay too low and curing cycles remain too short. Inadequate heat interrupts polymer cross-linking, leaving the internal elastomer under-cured, spongy, and structurally weak. Many engineers believe flawless surface aesthetics guarantee solid manufacturing quality. In reality, hidden internal defects represent the most dangerous operational hazards. Let us review the real inspection data from this customer complaint. […]

Pre-Order DFM Checklist for Custom Silicone Molds Are you planning to order a custom silicone mold? Stop. Before you pay for tooling, run this DFM (Design for Manufacturability) checklist. This guide is written for buyers, not just engineers. Let’s make sure your custom silicone molding order is right the first time. 1. Material Selection (LSR vs HCR) Choosing the wrong silicone type is a costly mistake. Liquid Silicone Rubber (LSR) is great for high-volume, precision parts. High Consistency Rubber (HCR) works better for general industrial parts. Client mistake: "I just need silicone." No. Specify the hardness (Shore A), color, and grade (e.g., medical-grade LSR). Pro tip: If you need FDA- […]