A simple way for 8% less injection molding waste
In a hall near Piaseczno, 112 kilograms of defective parts were thrown into the trash every day. The owner thought this was a cost built into the business, but we found a way to recover this money without buying new machines. It was enough to focus on specific cycle settings that operators often forget in a hurry.
Where was the money leaking on the floor?
In this specific company, 7 older type injection molding machines were running, mostly from 2014-2016. During our first walkthrough, we noticed that waste containers filled up faster than the finished goods warehouse. Every kilogram of wasted polypropylene cost the plant about 6.40 PLN. Given the scale of production Mr. Andrzej ran, those 112 kilograms per week meant a loss of around 2,860 PLN per month on raw materials alone, not counting electricity and labor.
The problem did not lie in the machines, but in the lack of control over the cooling process. Operators, wanting to meet the quota, shortened the cycle time by fractions of a second. It seemed to them that they would make more pieces this way, but in reality, the parts came out insufficiently cooled and deformed once in the box. This is a classic mistake in halls where only speed counts, and no one checks how many of those made pieces are actually fit for shipment to the customer.
We did a quick test on one shift. We pulled 47 parts from the bin, and every one of them had the same defect – material shrinkage in the same spot. This was a clear signal that the mold temperature was drifting and no one was controlling it. At Orzeł Strategii Group, we don't believe in magic; we believe in a thermometer and a stopwatch, so we started our corrective actions there.
Shortening the cycle by 2 seconds gave more pieces, but 12% of them were pure scrap.
Changing the temperature by 4 degrees
The first step was to stabilize the cooling temperature. It turned out that the thermostats on the machines were miscalibrated by about 4.2 degrees Celsius. This seems small, but for thin-walled plastic parts, it's the difference between a product and trash. We set the parameters according to the material's technical datasheet, which we dug up from the technologist's office and which hadn't been opened in three years.
We also introduced a rule that the operator cannot change the injection time without the foreman's consent. We extended the holding pressure time by exactly 1.8 seconds. Although the machine worked those two blinks of an eye slower, suddenly waste stopped falling into the bin. Process stabilization took us about 6 hours of work on two key machines that generated the largest raw material losses across the entire week.
The owner was skeptical because he feared productivity would drop. However, we calculated on paper for him that it's better to have 98 good pieces per hour than 105 pieces, 15 of which have to be ground up and thrown back into the regrind. Regrind never has the same properties as virgin material, so every such operation reduced product strength, generating further complaints from recipients in Germany.
Results after the first month
After 24 days of implementing the changes, we checked the weight of the waste. From the initial 112 kg per week, we dropped to 31 kg. This is a decrease of over 68.4% in the waste category, which translated into 8.4% savings on total raw material consumption on a monthly scale. In Mr. Andrzej's pocket remained an additional 2,140 PLN of pure profit, which he previously simply hauled to the landfill as production waste.
To show employees the importance of the problem, we set up a simple board with results on the hall. Every morning, the foreman wrote down how many grams of waste the previous shift generated. This bit of healthy competition made people watch the machine settings more closely. Honestly, it was the cheapest motivational method we ever implemented – it cost as much as a marker and a scrap piece of sheet metal.
No fluff: not every company needs new robots for millions. Often it's enough for someone from outside, like Orzeł Strategii Group, to step onto the floor, smell the grease, and check the basics that were forgotten in the daily rush. These 8% savings are often a matter of 'to be or not to be' for a small plant facing larger competition with lower margins.
We saved 2,140 PLN per month on raw material alone, without changing a single machine.
How to implement this for yourself?
Start by weighing what you throw away. Most production heads in Poland know how much raw material they buy, but only 23% of them accurately weigh waste by specific machine. If you don't have this data, you're operating in the dark. Buy an industrial scale for 400 PLN and start recording results for 11 business days. This will show you which injection molder is your biggest problem.
Also check the real temperatures on the molds using a pyrometer. Don't trust what the machine screen displays, especially if it's more than 5 years old. Sensors are often dirty or damaged, and a difference of 3-5 degrees is a standard that kills your margin. At Orzeł Strategii Group, we always start with such basics because they give the fastest return on investment.
If you feel like you're losing money on the floor but don't know exactly where, let us know. We'll come, walk through your plant, and in 2 hours we'll tell you where the money you're not picking up is lying. We don't promise miracles; we promise specific numbers and solutions your mechanic will understand in 5 minutes without reading a manual.
