Clamping Equipment

A brief description of the various types of high-volume clamping equipment available today. September 20, 2008

Reprinted with permission from MLS Machinery, Inc.

Clamps Case/Feed Through
Clamps Clamp Carriers
Clamps Frame/Door/Misc.

Clamps Case/Feed Through
Case clamps are clamping devices that will take a complete cabinet, when being assembled, and press it together to square the cabinet. It will be left in the clamp until the glue cures or it has been stapled or screwed together.

Case clamps come in a couple of different formats. Manual case clamps are either hand or air operated. Case clamps usually stand vertically from the ground, are not very deep but are normally quite long (16-20 long) and stand about 7-8 high. They have cylinders, normally air operated, that are set to the approximate size of the cabinet. Once the cabinet has been placed into the clamp a foot pedal or button is activated and the clamps come in and force the loose parts of the cabinet together.

Cylinders are normally on the top and one side of the case clamp. Some case clamps are double acting - in plain words, they allow two cabinets to be placed in the clamps at the same time so that one can be worked on while the other is drying. In this case the cylinders would be on top and two sides, while the sides would open and close manually to accommodate the size of cabinet.

There are also electronically controlled case clamps which have a conveyor feed which automatically brings the incomplete cabinet into the clamp where a magic eye reads the size of the cabinet as it goes into the machine. This now presets the cylinders as opposed to the manual system. The clamps come down electronically and will press for a certain pre-programmed cycle time and then release; once completed, the cabinet will come out on the other side of the conveyor.

Clamps Clamp Carriers
A clamp carrier is used to assemble numerous pieces of pre-glued solid wood "strips" together to form a solid wood panel. For example when you see what you think to be a solid piece of wood such as a butcher block or cutting/carving board or a solid wood table it may look to be a solid piece of wood, however in most cases it is not, they are strips of wood glued together. Once a tree has been cut down and the bark and defects removed you might land up with miscellaneous strips of solid wood from one inch to 12", or maybe a little wider, depending on the width of the tree, as you will see in a lumber yard. If there is a need to make a 24 or 26" wide cabinet or a very wide table these, strips of one inch to six inches wide material have to be glued together in a special way. In another category we will cover multiple rip saws and straight line rip saws, for cutting this wood, and will discuss the importance of these types of machines when being used for a glue application as in this case.

A clamp carrier basically comes in various lengths. The normal standard clamp carriers are 8'6" wide. They also come in 4'6", 6'6" and sometimes can be up to 16' long especially in the manufacturing of truck flooring. Most standard clamp carriers have six clamps per section. Every glued panel must be attached with a minimum of two clamps. When we talk about six clamps per section you could possibly place three glued panels along side of each other, as long as they will fit into the length of the particular clamp carrier, in a single section. This means each panel that is now being clamped together has a minimum of two clamps on each piece. The longer the piece of wood the more clamps you should use. The clamps themselves are normally three inches deep depending on the thickness of the wood and in certain cases customers with particular applications might require up to seven inch depth, but that is not the norm; most clamps are also 32" wide, which means you can put strips of wood in up to 32" depth making a table top that would be no wider than 32" when complete. Larger clamps are available if required for special applications. In some cases the clamp carrier might only have two clamps and some might have say 10 per section, etc., this depends on the application.

You could have numerous sections in a clamp carrier. The more sections, the larger the machine. A 60 section clamp carrier could be as long as 30'. Therefore to recap, a standard clamp carrier would be 8'6" wide, will say have 20 sections and each section can have six 32" clamps that are 3" deep.

The wood that has been clean cut (called a glue joint cut) is glued on one edge. Two edges are butted together and placed into a section of the clamp carrier using at least two clamps. Once the section is full the clamps are tightened to press the wood together. The clamps are tightened either manually one at a time on a manual clamp carrier or can be tightened by a 'robot' that travels along the front of the machine and automatically tightens the clamps; therefore if you hear people talking about automatic clamp tightening this is what it is. Most times a panel flattener comes with the machine which will press any bowed strips of wood down into the clamp before the clamps are tightened thereby giving nice flat pieces once dried and released. Once the section is completely full, the section will be rotated either manually or automatically, the whole section that was worked on will be moved towards the back of the machine while the operator now works on the next section; this is repeated until all the sections are full. Once the original section comes back to the operator, the pieces should be dry so that he can take the completed panels out for further operations such as planing and sanding.

Some small manual machines for small shops might only have six sections which turn on a central drum. Clamp carriers generally take a lot of space in width, length and height.
Taylor and Black Brothers are two of the most common manufacturers.

Clamps Frame/Door/Misc.
There are a number of clamping devices discussed in other sections, such as chair clamps and clamp carriers. There are other clamps that are used to attach a heavy solid wood edge to, as an example, an elliptical table top used in boardrooms. It is difficult to attach this curved piece of solid wood to the top so a specially designed clamp is used to hold the wood in place until the glue has cured or dried.

Other clamps would be frame clamps which normally stand vertically; some, however, are horizontal. A complete door or window frame can be placed in the clamp, and it will be clamped together so that the dowels or the construction device that is used can harden and set up at the same time while the frame is being made square. The frame is placed on a ledge vertically while air cylinders, or in certain cases hydraulic cylinders, clamp the parts from different angles and press the door or window frame together. These machines are quite long because of the parts that are being made.

Kitchen doors can be assembled in a similar manner. A number of doors are placed on a flat table having numerous air cylinders that can be located into various parts of the table. The lay-up table is normally pre-drilled with a number of holes at various increments for example at 3" centers. The clamps can be located in any one of these holes depending on the size of the door. Numerous kitchen doors are placed in this clamping device at the same time. The various clamps which are pedal activated lock the kitchen doors together and square them at the same time. There are certain applications where picture frames will be assembled in a similar manner using special staples to assemble them once squared.

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