Maintaining efficiency and profitability in plastic processing is dependent on many variables, and an important factor to consider is the quality of your purging procedures.Many plastic processors fail to use the appropriate purging compounds while others fail to implement proper purging procedures – or a combination of both. Both issues significantly reduce your profitability and often lead to hours of machine downtime.
Additionally, operators often take purging shortcuts and use the “auto-purge” feature available on most injection molding machines. This practice wastes purging compound and increases job change duration, but the resulting machine downtime in the future is far more costly.
Learn three ways in which poor purging procedures cause longer machine downtime for your facility:
1. Prolonged Color Or Material Changeovers
Failure to engage in proper purging procedures often leads to prolonged color or material changeover due to contamination or excess residue.
It can take several hours – eight to ten hours with a larger machine – for a color or material change if you keep running the next resin, color or regrind until the changeover is complete. This long machine downtime is wasteful in material consumption, time and labor. It’s also a lost opportunity for your business, as you’re not making sellable parts during this time.
To ensure the quickest, most efficient color or material changes, it’s important to purge your machines on a periodic basis.
2. Unnecessary Screw Pulls
In the plastics processing industry, manual screw pulls are a necessary cleaning procedure on occasion. However, if performed too frequently, they prove costly and detrimental to your bottom line.
There’s another side effect of manual screw cleaning. Cleaning a screw with a wire brush or other abrasive tools may damage and will erode the screw over time, limiting its life span. Manual cleaning can also create gouges and scratches where material and contamination can hang up. On the other hand, preventive maintenance and purging minimize the need to take such drastic measures – extending your screw life in the process.
3. Color And Carbon Contamination
Instead of proactively planning with an effective purging process, many plastics processing companies choose a reactive method of fixing problems as they occur. But taking this approach often leads to color and carbon contamination in your machines.
When a previously run color/resin or black specks appear in the molded parts, it’s a clear sign of contamination. Contamination in hard-to-clean areas – such as the nozzle tips, hot runner, melt pump, or die – may cause color streaks in molded or extruded parts even if the barrel and screw are clean, leading to excessive downtime.
Color and carbon contamination affect your profitability in the following ways:
- Scrap rates build up to an excessive amount, resulting in unplanned downtime due to a manual screw pull.
- Scrap rates and downtime prevent you from hitting planned production rates.
- A higher-than-quoted scrap rate drives down profit margins and increases the probability of late shipments, resulting in customer dissatisfaction.
Avoid downtime and reduced profitability by following the specific purging tips your supplier provides.
Poor purging procedures have a detrimental effect on your business’s bottom line. To improve your profitability, start taking calculated measures to maximize efficiency by adopting preventive purging procedures. Taking a proactive approach to your purging process leads to reduced machine downtime, scrap rates and customer rejects.
Learn more about improving your profitability with proper purging procedures.
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