Recovering 3,800 PLN monthly on plastic waste
Analysis of data from injection molding machines showed that machines were starting too early. A data-driven schedule change drastically reduced the amount of defective casts.
The Plast-Tech plant in Sosnowiec was losing money on every morning startup. Injection molders were producing scrap because no one was monitoring the exact mold heating moment before starting the first batch.
The challenge
At the facility on ul. Kombajnistów, 8 injection molders are running. For 4 years, no one calculated exactly how much raw material ended up in the bin between 6:00 and 7:15 AM. Operators turned on machines too early to meet the plan, but the temperature wasn't stable. Consequently, the first 12-15 casts from every machine were only fit for regrinding.
Analysis showed that the company threw away 114 kg of PP and PE granules monthly in the form of defective parts. Losses include not only material but also grinder labor and employee time spent sorting this waste. The system should make work easier, not add more clicking, so we had to find the cause in numbers, not in shift manager guesses.
Our approach
We entered the floor in May 2023. Instead of installing expensive sensors, we connected to existing PLC controllers on 3 selected test machines. For 19 business days, we only collected data on temperature and cycle time.
Numbers don't lie if you know how to read them. It turned out machines were starting on average 14 minutes too early relative to optimal thermal stabilization. Our team (3 people: analyst, automation engineer, and implementer) developed a simple start-block algorithm until parameters enter the green zone.
The solution
We introduced a digital schedule integrated with injection parameter control. We installed a simple display at each machine showing the time remaining until a safe start. No more manual transcription of data into the manager's notebook – now every batch is logged automatically.
The most important change was a physical 'Start' button lockout linked to the mold temperature sensor. If the temperature drops below 192 degrees Celsius, the machine won't start. This simple solution stopped the plant from milling empty runs. The shop floor must earn, not stand idle, and certainly not produce trash.
Results
By tightening morning startups, Plast-Tech reduced technological waste generation by over three-quarters.
Timeline
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May 2023Audit of cycle counters and temperatures on 8 machines
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June 2023Installation of data loggers and startup error analysis
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July 2023Implementation of start lockout and operator panel
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August 2023Performance testing and sensor calibration
"I was afraid these charts would just add more work at the computer. But the temperature lockout actually made things easier because operators no longer have to guess if the machine is ready."