Miller Electric KC237900 manual Maintenance Schedule Frequency, Weld Cables, Internal Cleaning

Table 6-1. Maintenance Schedule

Frequency*	Maintenance
Every month.	Units in heavy service environ-
	ments:
	Check labels, weld cables, clean
	internal parts.
Every 3 months.	Check weld cables (see Section
	6-1A).
Every 6 months.	Check all labels (see IMPORT-
	ANT block, Section 6-1). Clean
	internal parts (see Section 6-1B).

*Frequency of service is based on units operated 40 hours per week. Increase frequency of maint- enance if usage exceeds 40 hours per week.

A. Weld Cables

Every three months inspect cables for breaks in insula- tion. Repair or replace cables if insulation breaks are present. Clean and tighten connections at each inspec- tion.

B. Internal Cleaning

Every six months blow out or vacuum dust and dirt from the inside of the unit. Remove the outer enclosure, and use a clean, dry airstream or vacuum suction for the cleaning operation. If dusty or dirty conditions are pre- sent, clean the unit monthly.

6-2. TUNGSTEN	ELECTRODE	(Table 6-2,
Figure 6-1 And Figure 6-2)

Use Table 6-2 to select the correct size and type tung- sten electrode. Prepare the tungsten electrode using the following guidelines. A properly prepared tungsten electrode is essential in obtaining a satisfactory weld.

1-1/2 Times

Electrode

Diameter2-1/2 Times

Electrode

Diameter

AC And DC	DC Electrode
Electrode Positive	Negative	S-0161

Figure 6-1. Properly Prepared Tungsten

Electrodes

A. For AC or DC Electrode Positive Welding (Figure 6-1)

Ball the end of tungsten electrodes used for ac or dc electrode positive welding before beginning the welding operation. Weld amperage causes the tungsten elec- trode to form the balled end. The diameter of the end

should not exceed the diameter of the tungsten elec- trode by more than 1-1/2 times. For example, the end of a 1/8 in. (3.2 mm) diameter tungsten electrode should not exceed a 3/16 in. (4.8 m) diameter end.

B.For DC Electrode Negative Welding (Figure 6-1 And Figure 6-2)

CAUTION: HOT FLYING METAL PARTICLES can injure personnel, start fires, and dam- age equipment; TUNGSTEN CONTAMINA- TION can lower weld quality.

•Shape tungsten electrode only on grinder with proper guards in a safe location wearing proper face, hand, and body protection.

•Do not use same wheel for any other job, or the tungsten will become contaminated.

Shape tungsten electrodes on a fine grit, hard abrasive wheel used only for tungsten shaping. Grind tungsten electrodes so that grinding marks run lengthwise with the electrode. These procedures reduce the possibility of the tungsten electrode transferring foreign matter into the weld and help reduce arc wander.

Grind the end of the tungsten electrode to a taper for a distance of 2 to 2-1/2 electrode diameters in length. For example, the ground surface for a 1/8 in. (3.2 mm) di- ameter tungsten electrode should be 1/4 to 5/16 in. (6.4 to 8.0 mm) long.

For additional information, see your distributor for a handbook on the Gas Tungsten Arc Welding (GTAW) process.

TUNGSTEN PREPARATION: IDEAL

Stable Arc

Straight Ground

Flat

(The Dia. Of This

Flat Governs

Amperage Capacity)

TUNGSTEN PREPARATION: WRONG

Arc Wander

Point

Radial Ground

S-0162

Figure 6-2. Tungsten Preparation

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