Choosing the right heat sealer can be stressful, but with JTE it doesn’t have to be. We have created this overview of the various types of heat sealers with the hope that it will help to simplify the process of finding which one is best for your material type. When you are in the process of trying to select the best heat sealer for your material, there are a few key things to keep in mind. For example, what is the thickness and type of the material that you plan on sealing? Are you familiar with and have an overview of the types of welds needed to create your end product? If you have the answers to these questions ahead of time, it will make the selection process run so much smoother. To start, it is important to know what a heat sealer is, so for those who are unsure, a heat sealer is a machine that is used to seal plastic material using heat. Many people also use the term “heat sealer” for an RF welder or high-frequency welder. In this case, the “heat” is created by the spinning plastic molecules reacting to the electromagnetic wave generated by the RF machine. Because of the molecular nature of the weld, this is often the most reliable and efficient way to “heat seal” plastic materials.
There are many other types of heat sealers, but the two main types are impulse sealers and direct heat sealers. In this blog post we will cover which sealer is best for common material types starting with:
This type of sealer requires no warm-up time and seals by applying pulses of energy, under pressure, and the pressure is continued until the material cools down enough. Impulse sealers are best used on thermoplastic materials that are thin and lightweight. This includes polyethylene and polypropylene materials like Pilofilm, Saran, and Nylon. They can also be used on bubble packs, padded mailers, foil, coated bags, Kel-F, Polyflex, Mylar, and Tyvek.
There are different types of impulse sealers, and the following will help to break down which sealer is best for your material, according to thickness:
- Hand Sealers: can seal poly material up to 10mil in thickness
- Foot Sealers (or Pedestal Type): can seal poly material up to 15mil in thickness
- Auto Sealers: can also seal poly material up to 15mil in thickness
- Double Impulse sealers: come with automatic and foot options, and are recommended for heavy duty applications as they can seal poly material up to 20mil in thickness.
- Sealers with Cutters: used to trim and seal excess material, like that found in tubing, in order to make customized bags
Overall, Impulse sealers are easy to use because they have no warm-up time. They are also extremely safe, as no component of the machine stays hot throughout the duration of the weld. Furthermore, electricity is only used during the sealing process, making these welders an economical option. The downside of an impulse sealer as compared to RF sealing, are the long cycle times for both sealing and cooling, no easy way to change the width, length, or shape of the weld, and no reliable way to weld through more than two layers. In addition, the downtime required to change out the nichrome wires that warp quite quickly far exceeds maintenance needs of an RF welder.
Direct or Constant Heat Sealers
Direct Sealers, which are also known as Constant Heat Sealers, maintain constant heat in the tool and use power as long as the machine is turned on. Because of this, direct heat sealers are often faster than impulse sealers, with no cool time under pressure required. Direct sealers are best used on materials such as coated aluminum foil, gusset bags, coated Kraft papers, poly cello films, waxed paper, cellophane, mylar, coated PP, and other materials that are thicker laminated.
Types of Heat Sealing Processes:
- Vacuum Sealing– this process removes air from the product before sealing it into an airtight package. Vacuum sealing is used to prevent oxidation, spoilage or corrosion. This process can be used with RF, impulse and direct heat sealing methods.
- Clam Shell Sealing– just as the name suggests, this process is for welding clam-shell packaging. RF welding is usually used and is more reliable for PVC or PLA materials used in packaging.
- Portable Impulse Sealers– lightweight and versatile, but sizing is limited.
- Hand Impulse Sealers– the most simple and economic sealer available. The sealing bar is lowered manually and approximately 6-20 packages can be sealed per minute. A variety of sizes are available, starting at 4” all the way up to 40”.
- Foot Sealers– This sealer is controlled by a pedestal sealing bar leaving your hands free, and it provides a faster seal than a hand sealer. This type of process can be used with both RF and Impulse Sealers.
- Automatic Sealers– these sealers are ideal for high production jobs. Because of the high production atmosphere, automatic sealers are needed for high volumes of standardized products. The press is activated automatically and often features a pre-set time cycle that allows for a fully continuous operation. Automatic systems mostly employ RF technology for optimum consistency.
- Continuous Band Sealers- Provide the fastest sealing operation and have no length limitations. Instead, bags are simply fed into the sealer while resting on a conveyor belt. There are several types of continuous band sealers available, with features including horizontal seal heads, vertical seal heads, tilting seal heads, left or right feeds, coding, imprinting, and gas purging. Band sealers used direct heat in many packaging applications.
When considering which sealer to use, it is important to factor in the size type and weld size of the material that you want to seal, as the size and type of the welder is dependent on this. It is recommended that you add one inch to the width of the material to be sealed as it makes it easier to handle. While impulse and direct heat sealing can be a good choice for thin materials and non-RF weldable materials such as PE and PP, slower cycle times, higher maintenance, and low versatility are important factors when considering the purchase of a heat sealer, and should be factored into the ongoing costs of ownership.