Preventive Maintenance

5S in injection molding is the Japanese lean methodology — Seiri (Sort), Seiton (Set in order), Seiso (Shine), Seiketsu (Standardize), Shitsuke (Sustain) — applied to the press floor, the mold storage area, the resin room and the tool crib to cut waste, shorten changeovers and prevent contamination of plastic parts. The framework comes from the Toyota Production System and is the entry point to lean manufacturing in plastics processing. Adopted correctly, 5S typically reduces setup time by 20–50 %, drops scrap from contamination, and is often the prerequisite for advanced practices such as single minute exchange die (SMED) and rigorous preventive maintenance. ## The five S's translated to the mold shop | Pillar (JP) | English | What it means on an injection floor | |---|---|---| | Seiri | Sort | Remove obsolete tools, broken inserts, dead drums of resin, expired colorants. | | Seiton | Set in order | Shadow-boards at every press; one labeled home for each torque wrench, hose, drying hopper. | | Seiso | Shine | Daily wipe-down of platens, nozzle area, parting line; sweep regrind dust; clean dryer filters. | | Seiketsu | Standardize | One-page setup sheets, color-coded resin bins (e.g. red = ABS, blue = PC), photo-standards at each cell. | | Shitsuke | Sustain | Weekly 5S audits scored 1–5, posted KPI board, supervisor walk-throughs. | The original Japanese spelling matters: every term starts with "S" in romaji, which is why the method is universally known as 5S. ## Why 5S is critical specifically in injection molding A plastics plant is not a metal-cutting shop. Three molding-specific risks make 5S non-negotiable: 1. Contamination of melt. Even a single pellet of the wrong resin in the hopper can scrap a whole shot of a medical or optical part. Sort + Standardize keep resin streams separated by color-coded bins, dedicated scoops and labeled hopper loaders. 2. Mold damage during changeover. A misplaced eyebolt, missing clamp or hidden hand-tool causes dropped tools and parting-line dings. Set in order means every clamp, locating ring and water jumper has a marked slot on the changeover cart. 3. Process drift. Drips of oil on the platens, dirty thermolator hoses or clogged purge bins push cycle time up shot after shot. Daily Shine routines protect the stable process window the engineer validated. ## A practical 5S checklist for an injection cell - Sort: any tool not used in the last 90 days is red-tagged and moved out of the cell. - Set in order: shadow-board for wrenches, allen keys, brass picks; labeled hooks for water hoses; numbered storage for inserts. - Shine: end-of-shift 5-minute clean — platens wiped, ejector area cleared of flash, regrind bin emptied, dryer filter inspected. - Standardize: laminated setup sheet at the press with screw RPM, back pressure, barrel zones, mold open/close speeds and a part photo. - Sustain: weekly audit by a team leader using a 25-point checklist; score posted on the cell board; corrective actions in a Kaizen log. ## 5S applied to the mold storage area Mold storage is where most plants lose 5S discipline. A disciplined storage program includes: - Numbered racks with a unique location per mold and a database link. - Rust-preventive (VCI paper or oiling) before storage, recorded on the tool history card. - Maximum 3 molds high stacking and minimum 50 mm clearance for an overhead crane sling. - Pre-storage cleaning of cavities — no plastic residue allowed before the mold goes back. ## Common pitfalls - Treating 5S as a one-off "clean-up day" instead of a daily rhythm. - Buying expensive shadow-boards before the Sort step — you organize tools you should have thrown out. - Auditing without consequences — the score has to drive Kaizen actions, otherwise the system decays. - Forgetting the resin room and the regrind area — they are part of the value stream, not "support". ## Related terms See also: lean manufacturing, single minute exchange die, preventive maintenance, cycle time. ## FAQ ### What are the 5 S's of 5S? Sort (Seiri), Set in order (Seiton), Shine (Seiso), Standardize (Seiketsu) and Sustain (Shitsuke). In an injection-molding plant they translate to: discard obsolete tooling, give every tool and resin bin a marked home, keep platens and dryers clean, write one-page setup sheets, and audit the cell every week. ### How does 5S benefit injection molding specifically? It directly attacks the three biggest molding losses: resin contamination, changeover time and process drift. Plants that run 5S well typically report 20–50 % shorter changeovers, double-digit drops in contamination scrap, and far fewer near-misses around moving molds and platens. ### Is 5S the same as housekeeping? No. Housekeeping is just cleaning. 5S is a system: it includes cleaning (Shine), but also discarding unused items (Sort), engineering tool locations (Set in order), writing standards (Standardize) and auditing discipline (Sustain). 5S is also the foundation for single minute exchange die and Total Productive Maintenance. ### How often should a 5S audit be done on a molding floor? Most well-run plants audit every cell weekly with a 20–30-point checklist, plus a monthly cross-plant audit by a leadership team. Scores are posted publicly and Kaizen actions tracked to closure.

Lean Manufacturing is the systematic methodology to reduce the seven classic wastes (overproduction, waiting, transport, over-processing, inventory, motion, defects) in any production system. In injection molding it attacks press idle time, start-up scrap and long changeovers. ## Pillars of Lean in molding - Continuous flow: minimize inventory between press, secondary ops and packaging - Pull (kanban): produce only what the next customer requests - Jidoka (built-in quality): automatic scrap detection by vision or sensors - Standardization: start-up checklists, master parameters and SMED - Continuous improvement (kaizen): small daily improvements by the operator ## Common Lean tools in molding plants - 5S for orderly workstations and tool cribs - SMED to slash mold-change times (target <10 min) - Total Productive Maintenance (TPM) for machine availability - OEE (Availability × Performance × Quality) as the headline KPI - Andon: visible alerts for stops, scrap or changeovers ## Typical indicators - World-class OEE in injection molding: 85 % - Target mold-change time: <10 min (SMED) - Acceptable scrap: <1 % in stable production - Order-to-ship lead time cut by 40 – 70 % after implementation ## Common pitfalls Rolling out tools without changing culture, copying Toyota without adapting, chasing metrics (OEE) without attacking root cause, and abandoning 5S discipline at the first demand spike.

A quality system (quality management system, QMS) is the documented set of procedures, records and responsibilities a molding shop uses to consistently make parts that meet specification — and to prove it. It turns "we made good parts" into "we control the process that makes good parts and have the evidence." In injection molding it ties the molding process, the people and the paperwork together. ## What it covers in a molding shop - Process control: documented setups, target windows and monitoring of molded part dimensions, weight (cavity weight) and dimensional stability — ideally developed with scientific method scientific molding so the process is robust and repeatable. - Incoming & material control: verifying resin against the material data sheet, drying records, lot traceability and controlled regrind ratios. - Validation: IQ/OQ/PQ (installation, operational, performance qualification) to prove a new mold or process makes good parts across its window — required in medical and automotive work. - Maintenance & changeover: preventive maintenance schedules, single minute exchange die and 5 s to keep the cell capable and organized. - Records & improvement: inspection data, non-conformance and corrective action, reducing scrap over time. ## Common standards ISO 9001 is the general QMS standard; IATF 16949 adds automotive requirements; ISO 13485 covers medical devices. Certification signals a customer the shop runs a real, audited system. ## Why it matters A quality system is what makes good parts repeatable and provable — it lowers scrap and returns, satisfies regulated customers, and turns problem-solving into a documented, systematic loop rather than firefighting. ## Related terms - See also: scientific method scientific molding, molding process, material data sheet, preventive maintenance, scrap ## What is a quality system in injection molding? The documented procedures, records and responsibilities a shop uses to consistently make parts to spec and prove it — covering process control, material verification, validation (IQ/OQ/PQ), maintenance and continuous improvement, often certified to ISO 9001 or IATF 16949. ## What is the difference between ISO 9001 and IATF 16949? ISO 9001 is the general quality management standard for any industry; IATF 16949 builds on it with stricter automotive-specific requirements (PPAP, APQP, traceability) for suppliers to vehicle manufacturers. ## Why does a molder need a quality system? To make conforming parts repeatable and provable: it controls the process, documents material and maintenance, validates new tooling, lowers scrap and returns, and is usually required to supply automotive, medical or other regulated customers.

A scheduled stop is planned, intentional downtime when the machine is deliberately taken out of production — for breaks, shift gaps, no-demand periods, changeovers or preventive maintenance. Unlike a breakdown, it is known in advance and built into the plan. ## Scheduled vs unplanned stops - Scheduled (planned): breaks, meetings, planned maintenance, no orders, tooling changeovers — excluded from the productive time used to judge availability. - Unplanned: breakdowns, jams, material-outs — these hurt availability and OEE. ## In OEE A scheduled stop is planned downtime, removed from the calendar before computing planned production time, so it does not count against the availability factor of OEE (only unplanned stops do). How you classify a stop therefore changes the numbers — be consistent. ## Why it matters You cannot eliminate all stops, but you can shrink and concentrate them: batch maintenance into one window, cut changeover time with quick-change tooling and method (see single minute exchange die), and avoid turning a scheduled stop into wasted startup scrap or lost cycle time on restart. ## Related terms - See also: preventive maintenance, cycle time, molding cycle, single minute exchange die, scrap ## What is a scheduled stop in injection molding? Planned downtime when the machine is intentionally stopped — for breaks, changeovers or preventive maintenance — known in advance and excluded from productive time. ## What is the difference between a scheduled and unplanned stop? A scheduled stop is planned and excluded from availability; an unplanned stop (breakdown) is unexpected and counts against availability and OEE. ## How do scheduled stops affect OEE? They are planned downtime, removed before calculating planned production time, so they do not lower the availability factor — only unplanned stops do.