Amada 1-288-01, Operation Manual, Page: 97 / 144

CHAPTER 6: MAINTENANCE
HF28 DC RESISTANCE WELDING SYSTEM
990-372 6-9
Section III. Maintenance
Electrode Maintenance
When a welding schedule has been suitable for a particular welding application over many welds, but
poor quality welds are now resulting, electrode deterioration could be the problem. If you need to
increase welding current to maintain the same weld heat, the electrode tip has probably increased in
surface area (mushroomed), effectively increasing weld current density, thus cooling the weld. Try
replacing the electrodes.
The rough surface of a worn electrode tip tends to stick to the work pieces. So, periodic tip resurfacing
(dressing) is required to remove pitting, oxides and welding debris from the electrode. You should limit
cleaning of an electrode on the production line to using a #400-600 grit electrode polishing disk. If you
must clean a badly damaged tip with a file, you must use a polishing disk after filing to ensure the
electrode faces are smooth.
The best method of preventing electrode problems is to regularly re-grind electrode tip surfaces and
shapes in a certified machine shop.
Parts Replacement
Below is a list of the replacement parts for the Control. All items listed are a quantity of 1 each.
WARNING:
Only qualified technicians should perform internal adjustments or replace parts. Removal
of the unit cover could expose personnel to high voltage and may void the warranty.
Part Description
Amada Miyachi America
Part Number
Location
Input Power Line Protection Fuses F1 and F2:
HF28/240
HF28/400
HF28/480
330-071
330-092
330-092
Rear Panel
Control Power Protection Fuse F1 330-078 Power PCB
Input Power Selection Plug Set:
240 Volts
400 Volts
480 Volts
4-34314-01
4-34315-01
4-34316-01
Welding Transformer Chassis