When it comes to handling bulky materials, there’s probably no more versatile piece of equipment than the baler. Today’s balers handle a wide variety of scrap material, including metals, corrugated, wood, paper and the focus of this month’s spotlight - plastics. Choosing the right one depends entirely on what you’re baling, and the optimum throughput for your operation.

The most commonly baled plastics can be divided into two broad categories. First, there is PET, or PETE – known among chemists as Polyethylene Terephthalate. This is the familiar material that nearly all of the plastic containers for soft drinks, mouthwashes, peanut butter and salad dressings are made from.

Among the inherent characteristics of PET is “memory,” or the tendency for the material to spring back to its original form after pressure is applied. To resist the “spring back,” balers used for plastics often feature “restraining dogs” that keep compressed plastics from creeping up the walls inside the baling chamber. As pressure forces the material down, the dogs help keep the compressed load in place.

Tom Stevens, president of Wolverine Recycling Services, Inc. of Rochester, Michigan, distributor of baling and related recycling equipment throughout the Great Lakes region observes, “Many soft drink containers are returned with caps still in place. Baling them often requires that they be run through a perforator prior to loading in the baler. The perforator punctures the containers and allows air to escape as the ram compresses the load,” he said.

Due to the nature of the material, PET places special demands on the hydraulic system of the baler as well. “Baling PET containers can require ram face pressures of up to 225 psi,” said Stevens. Larger cylinders are needed to produce the additional force to assure a desired thousand pound bale.

The second broad category of frequently baled plastics is HDPE, or High Density Polyethylene. Examples of this type of plastic include milk, water and juice bottles, trash and shopping bags; detergent, yogurt and margarine containers. While there are plenty of similarities in the equipment, baling HDPE is less demanding than PET. According to Wolverine Recycling Services, Inc., “Balers used for high density plastics applications will typically have ram face pressures in the 70 psi range.”

In addition to special considerations for plastics, balers are commonly divided into two distinct design types. Vertical style balers feature rams that compress downward, pushing the load under force into the baling chamber. Well suited to smaller volumes, vertical balers require less space and are simple to operate, but are limited in the size of bales and the number of bales per hour that can be produced. Some of the more popular applications for vertical balers include retailers and other channel members who empty a variety of corrugated containers.

Horizontal balers are designed for higher volume operations. Mike Schwinn, sales manager for Maren Engineering said, “Cycle times are generally much quicker with a horizontal baler, because material is loaded into a feed hopper while the ram continues to cycle. Vertical balers are typically loaded by hand and can take as long as 50 seconds to cycle through. Some of the faster horizontal models take as little as seven and a half. Automatic wire tie systems boost production as well. When operators aren’t spending time tying bales, it speeds things up considerably,” he added.

Maintenance on a plastics baler varies, depending on the primary material being baled. Generally, the more sophisticated a baler is, the more maintenance it requires to keep it in top running form. According to Mike Schwinn, “The hydraulic components on a vertical baler should be inspected annually. Horizontal balers need monthly inspections and possible renewal work on the many more wear items, such as floor, ram, hold down bars, shear beam and knife, and the ram assembly,” he said.

Training is another important consideration for balers. Jose Martinez, president of J.M. Hydraulics, Inc., manufacturers of Baletech balers in Sun Valley, California said, “We stress safety first. On each installation, we spend time with customers to be sure everyone using the machine knows how to properly load and operate the baler. Best practices are reviewed and we cover the details so everyone is confident using the equipment.”

Regardless of size or type, balers play a vital role in recycling plastics. Reducing volumes and improving efficiencies help to ensure that materials are recovered and recycled by the most cost effective means possible.