Aluminum Foil Bag, Pouch and Envelope Production
Laminated aluminum foil pouches of various types are being used in increasing volume for food, candy, tobacco, drugs, cosmetics, speciality items and spare parts of many kinds. Protection of contents and promotional value are principal factors. Foil bags and envelopes are used principally for promotions and by boutiques and other speciality shops. Foil bags for retail ice cream items help insulate the contents from higher temperature surroundings. Generally, foil pouches, bags and envelopes are produced on the same equipment employed for their paper, film and paper/film counterparts. Foil bags and pouches are made from the laminated material which is web-fed or roll material, depending upon envelope style and size.
In a typical bag-making machine, the foil laminated stock is drawn from the roll and formed into a flat tube as it passes over a forming mandrel, or former. Simultaneously, the appropriate adhesive is applied to the edge of the web and the seam is completed by pressure when the joint passes between a set of rollers. As the web continues, gussets are added in the tucking-former section. A cut-off converts the web into bag lengths. Bottom glue is automatically applied to the trailing edge of each bag length tube. As it passes through the bottomer station, the bottom fold and seam are made, completing the bag.
The most common bag is the brown kraft grocery bag. It represents one of the four standard bag types, the automatic or self-opening style, commonly referred to as SOS. The SOS and the other three styles, flat, square, and satchel, are shown in here, wherein features of each style, together with common closure methods, also are given. All styles are produced from foil-laminated stocks.
The envelope is a special kind of flat bag, sealed on three sides, with a fold-over flap on the open side. Variations include open end, gusseted sides, re-usable closures, and such special features as die-cut windows and integral cushioning.
Because envelopes are used primarily for packaging flat items, they generally are made of somewhat more flexible materials than bags. Foil adapts well to these, but many of the foil bag materials are also used for envelopes. Typical bag/envelope materials include kraft, glassine, cellophane, and other plastic films, manila papers, and others. Again, as with bags and other containers, protective and display requirements are vital factors in determining the materials employed.
Closure variations for envelopes include the familiar string-and-button, several kinds of clasps, snap fasteners, metal seals, and latex adhesives that can be resealed after opening. The most used closure is the gummed flap for which there are several foil adhesives. It offers the greatest security, since the envelope is usually torn when this seal is opened.
Envelopes come in a wide range of standard sizes, as well as many special sizes and shapes that are custom made to fit the product. Some small parts envelopes are no more than one inch square, while an envelope for a zipper fastener may be 1 ½" wide and 18" long. Larger commercial envelopes are available up to at least 12" by 16".
The form-fill-seal pouch is today the largest single flexible packaging applications of aluminum foil. Pouches are formed continuously from the roll-fed laminated material as they are needed. Unlike most conventional bags, however, pouches are also filled and sealed immediately as formed. The pouch is one of the oldest automated package forms. Depending upon size, style and material, and type of product being packaging, such pouches can be formed, filled, and sealed at impressively high production rates.
Pouches can be divided into types, according to the way they are made. Three types are distinguishable, although each of these has many variations. This picture shows the basic three types - vertically formed pouch, the horizontal formed pouch, and the mandrel or shaped pouch. Vertical - there are two types of vertically formed pouches - the pillow pouch, made from one web, and the four sided seal pouch, made from one or two webs. The pillow pouch results when the single web is formed into a continuous cylinder as it is unwound, the edge of the web being joined in a vertical seal. The top of one pouch and the bottom of the next pouch are sealed in one operation, with the product being introduced into the pouch immediately thereafter. After it is filled, each pouch can be separated or still connected, pouches can be packed as a continuous belt or strip of any preset length.
Formed from two webs, the four-sided seal pouch has its side and bottom seals made before the product is inserted from the top. The top seal is then formed with the side and bottom seals of the next pouch. In both vertically formed types, a perforation generally is made between the pouches, making them easy to separate.
Horizontal - Horizontally formed pouches also can be made from one web or from two. Here, the single web fed pouch requires a seal on each side and the top, while the double web fed pouch is again a four side seal.
In shape, size and configuration, vertically made and horizontally made pouches show only minor differences, if any. The important differences are in the methods of filling the pouches, and the choice between the two frequently depends on the consistency of the product being packaged. Form-fill-seal machinery can be adapted to insert nearly any product form into a pouch; liquid, solid, semi-liquid, paste, powder, granular viscous, or free-flowing. Some products are more adaptable to vertical filling, while others are more suited for horizontal filling. Mandrel - the third type of pouch is formed or shaped around a mandrel, so that it is actually three dimensional before it is filled. It is more commonly made from one of the less flexible films. A familiar example of the mandrel pouch is the single serving jelly container used in restaurants.
Another type of laminated foil pouch which is becoming increasingly popular is the vertical form-fill-seal package, produced with or without gussets as desired. This is proving a superior package for snack foods and similar products.