Focus on Efficient Operations

by Staff

The pressure is on plastics processors to produce low-cost parts for their customers while still maintaining a comfortable profit margin. Energy and materials costs make up a significant portion of the production price for any item. Two U.S. plastics processors are having success in bringing those critical price points down and have shared their experience.

Reducing Energy Costs
Rising energy costs have hit molders where it hurts the most – the bottom line. Increasing utility costs affect the costs affiliated with production, which then need to be either absorbed by the manufacturer or passed along to the customer. What are molders doing to reduce their utility usage, thereby reducing their cost to manufacture? David Browning is the maintenance manager for Limmco, Inc., an injection molder in New Albany, Ind. Limmco has implemented energy-saving strategies that are lowering utility costs by thousands of dollars a year, with the help of the following strategies:

Power Factor Correction
Power factor correction adjusts the energy load, increasing the stability and efficiency of a utility network. Limmco worked in conjunction with its local REMC to bring in an energy consultant, E-Max, Inc. E-Max does energy audits for commercial and industrial properties, with results that can include reduced A/C load, lowered maintenance costs, and the ability to track energy savings.

As a result of the audit, Limmco installed capacitors for power factor correction at the incoming electric service panels, raising the company’s power factor from 84 percent to as high as 99 percent. This has led to a significant impact on Limmco’s electric bill.

Insulating Barrel Blankets
Insulating barrel blankets retain heat, directing heat back into the barrel rather than letting it escape into the air around the machine. When heat escapes, the effect is to reduce the efficiency of the machine and increase the ambient air temperature. A barrel blanket alleviates this concern, while also providing protection for operators – the insulating blanket can help employees avoid burns from hot equipment.Barrel blankets come in different widths and can be purchased off the shelf or custom-made with cuts or slits that will wrap around existing wires and cords.

Browning explained that Limmco became convinced of the benefits of barrel blankets when they brought in a power monitor device. “We hooked it onto one of our machines and recorded the energy usage over a 15-minute period when the machine was stable. Then we installed the blankets and ran the same machine, while recording another 15 minutes and we determined all of our power usage off of that.” According to Browning’s research and testing, the insulating barrel blankets installed on each of the company’s 14 molding machines, at $0.05/KWH, should save $4,928.56 per year on electricity. Browning was unable to precisely calculate the effect of the insulating barrel blankets on air conditioning costs, but is certain that there are savings in that area as well.

Rooftop Air Conditioning Economizers
When Limmco built a new facility, rooftop air conditioning units were equipped with economizers that use outside air to cool the building when the external temperature is lower than the internal temperature. The economizers work automatically, sensing the temperatures of exterior and interior temperatures and also can monitor the humidity. When the outdoor temperature is lower than the indoor temperature, a damper (or louvre-type system) opens to allow air from the outside to flow into the building, reducing costs to cool the building interior.

There may be benefits to employee health as well. A 2004 report by the Environmental Energy Technologies Division of Lawrence Berkeley National Laboratory and the Helsinki University of Technology Institute of Heating, Ventilation, and Air Conditioning (in conjunction with the U.S. Department of Energy) concluded that “The estimated financial value of the sick leave reduction from economizer use is three to eight times as large as the estimated energy cost savings. Thus, economizers may be much more cost effective than currently recognized.”

High Bay Fluorescent Fixtures
High bay fluorescent fixtures can provide energy savings over traditional 400 watt metal halide lighting fixtures. High bay fluorescent fixtures can use up to 50 percent less energy. Limmco has not yet implemented this change, but is looking at it for a future project. Browning said, “We have 30 fixtures and the calculated savings is $1903.20 per year in electricity cost, not counting the difference in heat generated. The lamps we have are 400-watt and they create a lot of heat. The high bay fluorescents don’t produce as much heat or use as much electricity, and they actually put out a better light.”

Rotary Screw Air Compressors
Another future project for Limmco is the purchase of a second rotary screw air compressor. When the second compressor is purchased, Limmco will add selectable ducting routed from the building interior (plant area) to the outside. “During the summer, we will route the heat from the air compressors to the outside,” explained Browning, “and during the winter we will keep that heat inside as required.” Limmco originally had a reciprocal air compressor, which can put out as much air as a screw compressor but is not as efficient, according to Browning. “We bought a screw compressor that is smaller, lighter, and which uses less horsepower. It will produce more air at the given pressure and takes up less space so we have room to bring more in as we grow.”

Using Materials Efficiently
Increasing oil and gas prices have impacted both the price of plastics resins and the cost to transport them from the originator to the processing facility. Using materials more efficiently once they’re in-house makes good business sense, and World Class Plastics, in Russells Point, Ohio, is a prime example of a processor making materials work for them, rather than against the bottom line.

The management of WCP took a look at waste materials and saw an opportunity for improvement, but even they didn’t realize how much the company’s material strategy would change based on the results of a simple experiment. In May of 2006, the company began tracking raw material scrap. A large cart was placed at the front of the building with four labeled trashbins for four types of scrap. Employees were asked to weigh and log the amount of scrap at the end of each shift. “When we were first starting this, we developed a tracking graph. When we made the scale for the graph, we put 500 pounds for the month,” explained Mark Seeley, president. “The next day when we came in, we had 750 pounds of scrap. And here we were, thinking that 500 pounds would cover us for 30 days.”

In fact, WCP was throwing away close to $50,000 worth (12-14 percent of raw material usage) of raw material each month. Strategies were put into place to reduce the amount of scrap used on the production floor and the company is currently down to $7,000 to $8,000 of waste (3-4 percent) per month.

The first, and perhaps most important, key to scrap reduction for WCP was awareness. Awareness alone caused scrap levels to be reduced 50 percent. Once the management and employees had an understanding of how much the high level of scrap was costing the facility, they began to look for more efficient material usage.

It follows that a processor who produces parts accurately and accord-ing to production standards will see a reduction in scrap. WCP works toward that efficiency by training operators to have an intimate familiarity with the equipment that projects are running on. Standardization in equipment plays a key part. Since its inception in 1994, whether it’s an injection molding machine or a piece of auxiliary equipment, an effort has been made to use only one brand of machinery, so an operator can go from one machine to the next without having to reorient themselves.

Seeley also recommends that processors understand the power of a material handling system. “We installed a Conair material handling system in July of 2006 and that’s proven to be successful toward reducing scrap caused by contamination and handling.”

Reducing Number of Material Types
A reduction in its materials base has made a significant difference for World Class Plastics as well. At one time, WCP was using more than 120 materials in its molding operation. Now the majority of the molding done at WCP (60-70 percent) is done with polypropylene. Scrap polypropylene can be recycled and sold, further reducing waste and providing a return on the original purchase price. More importantly, a bulk purchase price for one material is far more efficient than negotiating pricing for over 120 different materials in a variety of quantities. As noted in the 2007 Raw Materials Survey from MAPP (see page 18), processors are becoming successful in recommending lower cost equivalents to their customers. Reducing the number of material types also reduces the storage space required for storing resins.