Plastic Extrusion and Manufacturing Process

These are the three steps involved in making any plastic bag:

  1. Extruding Plastic Film
  2. Printing Bags
  3. Bag Making or "converting"

Blending and Mixing Resins
Clear LDPE (low density polyethylene) plastic resin in pellet form is vacuum fed from storage silos and blended with various additives as required for specific product applications. These mixes transform the plastic polymer to improve their basic mechanical, physical and chemical properties into a commercial product.
Additives combine to create the desired proprietary blends of clarity, strength, stretchability, sealability, scuff and tear resistance, UV protection, bacterial protection, surface appearance, slip resistance and other properties required for the finished product.
If coloured film is to be made, coloured pellets (called "Master Batch") are added in blends from 1% to 25% to achieve different opacities and virtually any colour imaginable.Numerous resins, both LDPE and Linear LDPE, are kept in stock to allow for the many diverse applications that are manufactured daily.

1. Extruding Plastic Film 
The blended resins are then fed into extruders and melted at 380F. Screw drives force the molten mixture through a precision die where air is introduced and a 'bubble' is formed. This process is known as "blown film extrusion".
Adjustments to wall thickness and diameter are made in this continuous bubble or tube. As it rises some 20 feet, it cools and is flattened and wound under tension into 50 - 200 lb. rolls.
Our line-up of extruders gives us the flexibility to regularly produce custom film orders. This allows also for quick order fulfillment where tubing may be available in as little as 2 or 3 days.

2. Printing Bags

From the extruders, the rolls of film are delivered to our print department. Flexographic stacked presses produce printed film in up to 10 colours with matte to gloss to metallic finishes.

A smaller press does the less complex jobs such as produce roll bag printing and other 1 or 2 colour jobs.

This versatility allows us to print small quantities of bags and also to handle huge press runs of a week or more. We can consistently meet deadlines while achieving consistent, quality results.

3. Bag Making or "converting"

Either plain rolls from the extruder line or printed rolls form our presses are delivered to the bag making area of our plant. A myriad of sizes and options are available in essentially 3 types of bag conversion: single bags, bags on rolls (perforated tear-off) or bags on wire wickets.

Roll stock is loaded onto bag making machines where repetitive bottom seal or side seal converting takes place to produce individual bags from the large rolls.Holes, vents, slits, perforations, handle punching, wicketting, header sealing and ziplocking are some of the many options available in each production run.

Special folding jigs allow for gusseting as required with high speed, automatic wire wicketting machines aligned for efficient production.

After the rolls of tubing are converted into one of many styles and types of bags, the bags are packed into boxes, stacked and wrapped on pallets in preparation for shipment.

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Even Reusable Bags Carry Environmental Risk

Published: November 14, 2010

There is no evidence that these bags pose an immediate threat to the public, and none of the bags sold by New York City's best-known grocery stores have been implicated. But reports from around the country have trickled in recently about reusable bags, mostly made in China, that contained potentially unsafe levels of lead. The offending bags were identified at several stores, including some CVS pharmacies; the Rochester-based Wegman's grocery chain recalled thousands of its bags, made of recycled plastic, in September. 
Concerns have proliferated so much that Senator Charles E. Schumer, a New York Democrat, sent a letter on Sunday to the Food and Drug Administration, urging the agency to investigate the issue. 
Reusable bags have maintained their popularity even amid charges that they become hothouses for bacteria. The recent studies, none of which were conducted by the government, found that the lead in some bags would pose a long-term risk of seeping into groundwater after disposal; over time, however, paint from the bag could flake off and come into contact with food.