An accumulation-type drawing system that has a succession of pulleys mounted on a framework above the machine. Wire passes from the die around a block, over an overhead pulley via a pulley on the waffle arm and on to the next die. A twist is thus imparted to the wire between each reduction. This difficulty is accentuated if for any reason one block of the machine has to be stopped for example when it is full. In this case all preceding blocks must also be stopped and where machines are equipped with an automatic control to stop full blocks this control also stops the preceding blocks. With double blocks only the full block need be stopped.

See Pre-drawer.

Slip-type machines are used for nonferrous wires and finer sizes in ferrous and alloy wires. They are generally wet-drawing, multi-hole machines in which the actual reduction must be greater than the inbuilt speed ratio between successive capstans. Typical slip-type machines are designed to provide at least 3% slip or speed difference at the penultimate block and around 1% additional slip per preceding draft. There is always 0 % slip at the finish or pull-out capstan. The capstan speed should always be equal to or greater than the wire speed at each draft. The hypothetical condition in which capstan speed is less than wire speed is called negative slip, which is an unacceptable condition.

A slip-type wet drawing machine that uses multiple capstans mounted on the same shaft. The individual capstans usually have progressively larger diameters to accommodate wire elongation.

Systems in which the wire takes the shortest path from one die round the block and straight into the next die. While the machine is being threaded up, the torque developed by each motor is adjusted until it is just sufficient to pull the wire through the die and in addition to provide a little extra pull through the wire itself to assist in turning the preceding capstan. This extra pull, known as “back pull,” ensures that the wire passes straight into each die, which is an important consideration, especially when drawing thick wires. The capstans are tilted in the direction of drawing to enable a substantial number of turns to be taken around each one and to permit the wire to run through the die to the bottom of the following capstan in a straight line.

Another term for a slip-type multiple die wiredrawing machine with one capstan per shaft. The capstans drawing the wire through each die are arranged to in­crease in speed to correspond with the elongation of the wire. This speed increase may be approximate; in which case the wire is made to slip on the capstans. Note: each capstan is the same diameter and only one capstan is mounted on each driven shaft. The speed of each capstan is determined by the gearing between the driven shafts.

See entries for reels.

High production speeds are dependent upon several factors: lubrication, shape of dies, efficiency of welds, rods, cooling of wire, specification of wire, handling facilities, methods of stripping, control of cleaning and feeding stock into machines. The speed of the machine itself often is the least difficult of the problems, efficiency being dependent upon the effi­cient control of the variable factors.

Ductility of carbon steel wire can decrease considerably as a result of strain aging if wire temperature is not kept down. For example temperature must not exceed 160°C (320°F) when drawing 4.4 mm (.173 in.) in diameter, patented 0.75% carbon steel wire. Since a temperature rise of 120°C (248°F) per pass can be expected when using reductions of 20 percent, effective inter pass cooling is essential, especially as the drawing machines used generally have very little wire accumulation on the block. The temperature can be reduced by several methods: water-cooling of the die, by an air jet, or by air or water-cooling of the capstan.

The continuous application of a tension force (back pull) against the direction the wire is being pulled through the die to reduce the compressive stresses caused by the nib of the die. The back pull cannot exceed the point where the stress exerted by the drawing force equals the tensile strength of the wire at the die exit. See Wiredrawing, Reactive.

Drawing in which soap powders or grease are used as lubri­cants and the wire is wrapped round the capstans a sufficient number of times to ensure that no slip occurs. The lubricant is placed in a container (die box) in front of the die and picked up by the moving wire as it passes through. Usually used for non-slip machines drawing ferrous wire above 0.61 mm, although some slip-type machines have also used dry soaps.

See Hot Wire Drawing.

An alternative term for back-pull wiredrawing, the name coming from the fact that in some cases the back-pull is obtained by differential gearing interposed between the pull block and the pull-back block.

Drawing of wire that is immersed in a liquid lubricant bath contain­ing soap solution, oil or soluble oil. Carried out on slip machines, usually for non­ferrous wire, and also for ferrous wire finer than about 0.92 mm (.036 in.). The wire and dies on wet-drawing machines can be more easily cooled, permitting highest speeds.

The accessory parts and materials that are used in the installation of wiring such as terminals, connectors, junction boxes, conduit, clamps, insulation and supports.

See Drawing, Wiring Diagram.

A hollow conduit or raceway through which wires are passed. A duct is used as a protective shield for the wires it contains. Unlike a cable or harness assembly, it permits the addition or removal of individual wires.

Continually test instruments for checking wired assemblies. These instruments detect opens, shorts and “mis-wires.”

The highest value that a device can withstand without breakdown.

Designation for Wattmeter.