Usage:
The usual means of measuring welding parameters when reconditioning undercarriage components by hard face welding has been to monitor the arc voltage and amperage. These variables, especially the amperage, control the heat input to the component and the rate at which weld metal is applied.
There are a number of factors which can affect the accuracy of the ampmeter readings obtained when welding undercarriage components. The meters installed on most welding equipment are not precision instruments. This will result in considerable deviation even if they are within calibration. The scales on these meters are usually quite small making accurate readings difficult. Poor maintenance can also result in loss of calibration or even failure of these meters to function at all.
Additionally, the operation of the constant voltage power sources used with most undercarriage rebuilding equipment can result in significant amperage variations. This results in wide swings of the meter making accurate readings impossible.
The panel control marked "amps" actually controls the speed of the wire feed motor. The amperage supplied by the power source varies as necessary to melt the wire at the rate the feed motor is advancing it into the arc. When the distance between the welded surface and the electrode tip varies, such as oscillating welding a roller tread with significant radius near the flange, there is rapid fluctuation in the amperage. These rapid swings of the ampmeter make accurate readings impossible.
The wire feed speed is easy to measure accurately as it is not subject to these fluctuations. A portable wire feed speed meter (Model K283) is available from the Lincoln Electric Corporation, P.O. Box 17115, Cleveland, Ohio 44117, U.S.A. This Digital Wire Feed Speed Meter can be obtained from any Lincoln District office or ARMCO Sales Distributors.
The "wire feed speed meter" is a light weight unit, which can be held in position by hand during operation. It can be used to measure the speed of either automatic or semi-automatic electrode wire with a diameter of 0.90-5.56 mm (.035-.219"). The meter shows the wire speed in inches per minute, and can be used on any machine where there is access to the wire during operation. At the present time, the Lincoln Wire Feed Speed Meter is available only to read inches per minute and not millimeters per minute.
Wire speed meter.
NOTE: On some meters, the letters "rpm" are shown on the clear cover of the dial face. This has no reference to the meter indication, which is shown in "inches per minute" as given on the identification plate on the meter.
The meter has a guide with a spring to hold the pickup shaft against the wire. A handle on the meter moves the guide away from the shaft when the meter is to be put on the wire. Both the guide and the shaft have electrical insulation to prevent shock from the current in the electrode wire. The wire speed is shown as a "digital readout" (number indication) on the dial, with an accuracy of plus or minus one inch per minute, and the instrument checks the dial indication at intervals of one second.
To use the meter, push the handle to move the guide away from the pickup shaft, and put the shaft over the wire. Be sure the wire fits into the groove in the guide as the handle is released, and the shaft is in correct alignment with the wire. Wrong alignment of the shaft with the wire, or any movement of the meter along the wire will have an effect on the accuracy of meter indications. To prevent movement, the recommendation is to hold the meter against a stationary support, like the wire feed tube or housing. With the meter in position, push the button (plunger) on the side of the unit to see the speed indication on the dial. For maximum service life, remove the meter immediately after the wire speed has been checked. Constant or long intervals of use cause more wear than necessary to both the guide and the meter.
Wire speed meter in operation.
Welding electrode wires used for the addition of hard surfaces on undercarriage components are not all the same. Wires from different sources (factories) can have differences in the density (weight) because of the thickness of the metal sheath (cover), and the core (inside) material. The chart that follows shows the wire feed rates at different current (ampere) settings for some of the available wires.
