Daily Maintenance Specifications for Plastic Injection Molds

Daily maintenance of plastic injection molds is a core process critical to ensuring continuous production, improving product qualification rates, and extending mold service life. It must adhere to the principles of "prevention first, cleaning priority, and regular maintenance." A standardized workflow should be established based on the mold structure and production frequency. The following is a professional translation of the simplified guide, outlining industry-recognized daily maintenance specifications.

1. Pre-Maintenance Preparation

Safety Confirmation

Before performing any maintenance, the injection molding machine must be stopped and powered off. The cooling water or hot oil circuits must be closed, and the mold must be allowed to cool to room temperature to prevent burns or mechanical injuries. The surrounding area should be cleared of debris and oil. Specialized tools must be prepared, including copper brushes, soft cleaning cloths, an air gun, anti-rust oil, high-temperature grease, and a torque wrench. The use of hard tools like steel wire brushes or screwdrivers to scrape the mold cavity surface is strictly prohibited.

Preliminary Inspection

A visual inspection of the mold is required before cleaning. Check the parting line for flash or impact damage, the guide pins and bushings for looseness or abnormal noise, the ejector pins for sticking, and the vents for blockages. Any obvious abnormalities should be recorded and addressed specifically to avoid exacerbating the issue through blind disassembly.

2. Daily Cleaning Maintenance

Immediate Cleaning During Production

Simple cleaning is required during production whenever there is a material/color change or if the machine is stopped for more than 30 minutes. Use an air gun to blow away plastic residue from the cavities, cores, ejector pin holes, and vents. Wipe oil and accumulated material from the parting line and slider rails using a soft cloth dipped in a dedicated cleaning agent. Ensure the cleaning agent is non-corrosive to the mold steel to prevent damaging mirror or polished surfaces. After cleaning, apply a thin, even layer of anti-rust oil to the parting line to prevent corrosion during downtime.

Thorough Cleaning After Daily Production

A comprehensive cleaning is required at the end of each production shift. Remove cold slug residue from the sprue bushing. Clean sintered carbon deposits from the vents using a copper brush to ensure unobstructed gas evacuation. Wipe away release agent residue from the cavity surfaces. For stubborn residue, gently clean after heating the mold to 50-60°C; violent scraping is forbidden. After cleaning, check the cooling channels for blockages using an air gun or water flush to prevent scale buildup that hinders cooling efficiency.

3. Maintenance of Key Components

Guide Components

Guide pins and bushings are critical for alignment. Inspect their surfaces daily for scratches, wear, or rust. Minor rust can be polished with fine sandpaper followed by an application of high-temperature grease. Severe wear causing excessive clearance requires immediate replacement. Sufficient lubrication is mandatory; apply a uniform layer of high-temperature grease to the guide pins before each shift to prevent galling due to dry friction.

Ejection System

Ejector pins, sleeves, and return pins must be checked daily for bending, deformation, breakage, or sticking. Slightly bent pins can be corrected, but severely deformed ones must be replaced. The ejector pin holes require regular cleaning. Apply ejector pin-specific grease to the pin surfaces before each shift to prevent wear and seizure. Additionally, check the ejector pin stop mechanism to prevent damage to the cavity from over-ejection.

Slider Components

For molds with slides, inspect the rails daily for cleanliness and wear, and verify the slider positioning and locking mechanism reliability. After cleaning debris and oil from the rails, apply high-temperature wear-resistant grease to ensure smooth movement. Check the fit clearance between the slider and core; excessive clearance causing flash requires adjustment or replacement of the wear plates.

4. Lubrication Specifications

Selection of Lubricants

Mold components requiring lubrication include guide pins/bushings, ejector pins, slider rails, return pins, and lifters. Different materials are required for different areas: high-temperature wear-resistant grease for guide pins and sliders to withstand molding temperatures; ejector pin-specific grease to prevent dilution by the release agent; and a small amount of anti-rust lubricating oil for threaded connections to facilitate future disassembly.

Lubrication Frequency

The frequency depends on production load. Under normal conditions, lubricate comprehensively before each shift. For high-load continuous production, replenish lubrication every 500 cycles. Apply lubricants moderately and wipe away excess to prevent contamination of the part surface. For molds in long-term storage, apply a sufficient amount of anti-rust grease to all lubrication points.

5. Storage and Protection

Short-Term Storage (Within 1 Week)

For short-term downtime, thoroughly clean the cavities, waterways, and moving parts. Apply anti-rust oil evenly to the parting line, cavities, and guide components. Close the mold and insert a uniform anti-rust spacer between the parting lines to prevent grease loss. Disconnect the cooling circuit and drain all residual water to prevent internal rusting.

Long-Term Storage (Over 1 Week)

Before long-term storage, disassemble vulnerable parts like ejector pins and sliders, clean them individually, coat with anti-rust oil, and store them sealed. Polish the cavities and cores to remove fine scratches and apply a special rust inhibitor. Spray the exterior with anti-rust paint and clearly label the mold with its number, specifications, and applicable products. Store in a dry, well-ventilated warehouse to avoid corrosion from humidity or acidic/alkaline environments.

6. Maintenance Record Management

Establish a daily maintenance logbook. Record the maintenance date, content, operator, mold condition, and results of any abnormality handling in detail. Records must be linked to the specific mold number for traceability of usage and maintenance history. After each maintenance session, a designated person must inspect and verify that the work is complete before the mold is returned to production. Any recurring fault hidden dangers must be reported promptly for a repair plan to be formulated.