Canadian Plastics

6 Ways to Find More Profit

It's a fool-proof formula. Bring together numerous blown-film specialists, managers and technicians, give them a few days to present, ask questions and shoot the breeze and you're bound to walk away w...

March 1, 2004   By Michael Legault



It’s a fool-proof formula. Bring together numerous blown-film specialists, managers and technicians, give them a few days to present, ask questions and shoot the breeze and you’re bound to walk away with a few good ideas for boosting the performance of your operation.

This year’s Resin-to-Revenue (R2R) technical symposium, organized by Future Design Inc. (Mississauga, ON), certainly provided attendees with all this and more. With respect to the goal of enhancing productivity and profits, some of the points made at the symposium were admittedly not new. Instead, as the speakers suggested, many processors fall short of implementing best practices not out of ignorance, but from lack of manpower, commitment by management, training deficiencies and other reasons. The experts all agree: if you’re not doing some or all of the following, you’re making less money than you could be.

1. Optimize material usage

With materials — resin, additives, colorants — accounting for more than 50% of the end product’s cost, reducing or limiting material usage should be a priority for processors wanting to pad their bottom line. Jim Cara, sales manager with Omya Inc. (West Columbia, TX), presented data from trials showing the addition of CaCO3 at levels up to 35% in 1 mil LLDPE film can boost output, measured in kg/hr, from 80% to 113%, as well as lower extruder amperage. The calcium carbonate used in the trials was treated and had a nominal particle size of 1.4 micron. The addition of calcium carbonate increased dart impact and tear strength in 1 mil film; however there was a slight decline in tensile strength. Cara said the results show that calcium carbonate is a viable replacement for more costly TiO2 and blocking additives, as well a filler for prime resin. A separate trial also demonstrated that addition of calcium carbonate allows downgauging of octene LLDPE film without a performance decline. He reported that analysis done on bags imported from Asia showed CaCO3 levels as high 15%.

“I encourage you to talk with your compounders to see how you may be able to use this technology to reduce costs and compete with off-shore producers,” Cara said.

Proper equipment and some basic color measurement knowledge can reduce usage of expensive color concentrates, reported Alex Rom-Roginski, president, Colortech Inc. (Brampton, ON). Rom-Roginski recommends use of gravimetric feeders; and also urges plant managers to ensure their operators know how to change the feeder setpoint corresponding to the desired let down ratio.

“Concentrate overusage is rampant in the industry,” he noted. Processors using lots of colorants can benefit from color measurement equipment because it provides hard data leading to better quality control.

2. Control film thickness

While there are numerous causes of film thickness (gauge) variation, the net result is lost profits. Gauge variation on the thin side can yield scrap, so it is not surprising that most processors choose to err on the side of thickness. Making measurements of bags supplied to several major retailers, Mark Anderson, sales manager at Plast-Control Inc., Newburyport, MA, found several brands to be over target weight by an average of 1.5% to 2.4%. On a line running 650 lb/hr, this translates to over $65,000 of additional material, energy and production costs per year.

Plast-Control’s gravimetric yield control systems help monitor and control gauge variation using a loss-in-weight programming technology. The average gauge is calculated and controlled against a requested target range. These values are compared against process data. The programmer calculates the necessary settings and makes adjustments by controlling either the screw speed or nip speed.

Thickness control technology should be considered whenever the ratio of the transverse direction variations to the machine direction variations is greater than two, said Robert Krycki, president of Future Design Inc. Hardware for controlling thickness, including on-line sensors, automated gauge control systems and air rings, can be retrofitted to older lines. Future Design’s Saturn Atlas is an air-cooling device that can be used with an existing high-performance air ring to reduce the gauge point-to-point variation in the transverse direction. The Saturn Atlas uses a series of air channels and independently-controlled valves to provide enhanced, precise control over bubble cooling.

3. Maintain bubble stability

An entire technical seminar could be devoted to the theory of bubble stability. Bubble stability (or instability) is the result of complex interactions between polymer, die and air ring. You can put yourself ahead of the game by utilizing a dual lip air ring, which generally provides finer control of bubble dimensions and frost line height. Problems such as draw resonance (hour glassing), helical instability, frost line height oscillation and bubble sag can be caused by a combination of factors involving the material, process set-up or equipment, reported Paul Waller, president of Plastics Touchpoint Group (Thornhill, ON). As a rule of thumb, if you’re observing consistent problems maintaining bubble stability, seek outside help. It’s a glitch that will put you in the red very quickly if not addressed.

4. Get the right screw/die for your process

Many processors assume, in error, that their screw has been correctly sized and specified for the particular job in production. Over time, however, with shifting customers and orders, plant managers and engineers can find themselves producing types of film on equipment originally built for other purposes.

“The screw and barrel are the heart of the extrusion process,” said Alex MacGregor, senior process engineer, Crompton Davis-Standard Corporation (Somerville, NJ). An optimized screw must be designed to accomplish a number of functions simultaneously, including solids conveying, melting, pumping, mixing and aiding chemical reactions. Different resins and film processing parameters require different screw designs (Table 1).

Using empirical methods and high-speed data analysis, Davis-Standard can help a customer optimize screw design for a specific application. Known process parameters needed for optimizing screw design include resin type (comprising grade, additives and blend details), output rate, melt temperature target and expected pressure.

Dual spiral dies incorporate two spirals per layer of die, effectively doubling the number of layers of film. According to Rafael Castillo, president of Dual Spiral Systems (Hamilton, ON), tests have shown that splitting the film layers results in higher MD/TD tear values, up to 50% improvement in gauge variation and other benefits.

5. Train your people, manage your floor

The weakest link in your operation is very often a poorly trained or uncooperative operator, as emphasized by a number of speakers:

“On one project, we worked for weeks to get the proper temperature profiles. Six months later we walked into the plant and all the extruders were set at 300F.”

(Alan Guy, regional technical service manager, Omya Inc.)

“The most grievous error is to allow an operator to run a machine at his level of comfort, instead of the full capability of the equipment.”

(Paul Waller, president, Plastics Touchpoint Group)

“There is an urgent need to raise the level of understanding of the operator. You need to get all the great technical information in here out to the plant floor.”

(Ben Propfe, director, Interplast, S.A. de C.V.)

A little knowledge can go a long way at the management level too. An Enterprise Resource Planning (ERP) program can improve access to production information and enhance decision making. PlastiSoft Corp.’s Tori-Flex is designed specifically for flexible packaging manufacturers. Tori-Flex provides a centralized data management program for all aspects of a film operation, including inventory, shipping, billing and quoting, according to PlastiSoft CEO, Jacob Aharon.

“Very few companies know what their true costs are and why or if they should be running a particular job,” sa
id Aharon. “This program allows you to track work-in-progress in real time and, at the end of the day, evaluate if you’ve made any money.”

Aharon noted that the recently upgraded version, Tori-Flex 6.14, comes with an advanced quote engine capable of creating accurate quotes for complex, multi-layer film structures very quickly.

6. Know your competition/market

Making decisions based on speculation or “the way the market used to be” can hurt you:

“One processor said ‘I can’t downgauge because my competitor is running at 0.9 mil and I can’t go to 0.7 mil because I’ll get a backlash from buyers’. Well, do a market survey and find out.” (Alan Guy, Omya Inc.)

“There are about 300 film shops in Mexico and, except for the larger ones, most are 10 to 15 years behind current technology.” (Ben Propfe, Interplast)

“Quality counts, graphics sell, don’t get complacent.” (Paul Waller)

“There are still many plants running old equipment with lots of downtime and maintenance. If you know how much this is costing, you can justify new equipment.” (Alan Guy, Omya Inc.)


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