AMI M8 Series User manual

OPERATION MANUAL
M8 SERIES WELD HEADS

Doc No. 7401231
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
NOTICE
This document and the information contained herein is the property of Arc Machines,
Inc. It is proprietary and submitted and received in confidence. It shall be used only for
the purpose for which it is submitted and shall not be copied in whole or in part without
the prior expressed written permission of Arc Machines, Inc.
The information in this document has been carefully reviewed and is believed to be
accurate.
Information and instructions in this document are subject to change and Arc Machines,
Inc. reserves the right to change specifications and data without notice.
WARNING
The nature of the GTAW process creates some POTENTIAL HAZARDS. In accordance
with international safety regulations the EXCLAMATION SYMBOL indicates that this
equipment is considered HAZARDOUS until an operator has been made aware of these
POTENTIAL HAZARDS by reading the appropriate Arc Machines, Inc. Power Supply
and/or Weld Head Operation Manual. The LIGHTNING FLASH SYMBOL indicates that
there are potential electrical hazards. The use and display of these symbols make it the
OPERATOR’S RESPONSIBILITY TO INSURE THAT HE HAS READ AND/OR BEEN
MADE AWARE OF ALL OF THE SAFETY-RELATED ITEMS CONTAINED IN THESE
MANUALS.
Publication date : November, 2011
Copyright 2010 by Arc Machines, Inc.
All rights reserved
REV DCO # CHANGE DESCRIPTION
DATE
APR
A E6181 First Edition 4/1/11 BL

Doc No. 7401232
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
Table of Contents
Chapter Description Page
1.0 Introduction………………..…………………3
2.0 Unpacking……………………………………3
3.0 Cable hook up……………………………… 3
4.0 Water Cooling………………………........... 5
5.0 Rotation (speed) Auto-Calibration……….. 5
5.2 Rotation (speed) Manual Calibration……. 6
6.0 Clamp Insert Installation………………… 7
7.0 Electrode Geometry & Installation………. 9
8.0 Shielding Gas……………………………… 13
9.0 Return-to-home (rotor) position
adjustment……………….…………………. 14
10.0 Cleaning & maintenance…………………. 16
11.0 Storage……………………………………. 17

Doc No. 7401233
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
1.0 INTRODUCTION
This manual covers set up and maintenance of the Model 8 series weld heads.
The operator should have a working understanding of the power supply being
used and should understand this manual before operating the weld head.
2.0 UNPACKING
When unpacking the weld head use extreme caution in removing the plastic bag
covering the cable connectors. Tools such a knife of other sharp object can cut
the cables.
3.0 CABLE HOOK UP
CAUTION
Always turn the power supply off before making any cable connections.
The Model 8 series weld heads come supplied with an integral 10ft (3 m) cable.
This cable is NOT connected directly to the power supply. It must be mated to
the power supply via an adapter pig-tail or adapter cable. Extension cables may
also be used. The use of an extension cable does not eliminate the requirement
for an adapter. If an extension cable is used, it is connected between the power
supply and the adapter. After making connections, slide the protective rubber
boots together. See fig. 1.
Fig. 1
Connect the power and ground fittings by pulling the brass ring back
and inserting the male fitting into the female fitting, until it is fully seated.
If it is not fully seated, it will leak water or potentially come apart.

Doc No. 7401234
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
3.0 CABLE HOOK UP (Contd.)
Fig. 2
To connect the male to female (chrome) gas fittings, unscrew the (4-40) socket
head screw to allow the latch to open far enough to fully seat the two fittings.
Lightly tighten this screw to prevent accidental disconnection of this fitting.
Fig. 3
Connect the motor control connector by aligning the key to the slot, and lightly
tightening the outer ring. Be careful not to cross-thread this ring.

Doc No. 7401235
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
3.0 CABLE HOOK UP (Contd.)
Fig. 4
Slide the boots together securely to protect the connectors and fittings from dirt,
and to prevent the power and ground connectors from coming in contact with
each other.
4.0 WATER COOLING
The Model 8 series heads are plumbed for water cooling, and are cooled via the
power supply’s (optional) cooling unit. Although water cooling is not required for
all applications, it should always be used when welding tube or pipe wall
thicknesses of 0.083” (2.1mm) or heavier, or when doing high-duty-cycle work.
Consult the factory for recommendations.
5.0 ROTATION (SPEED) AUTO-CALIBRATION
Before welding, the electrode rotation motor in the weld head must be calibrated
to the power supply. Most power supplies include an auto calibration function in
the software. Refer to the power supply operation manual for specifics on auto
calibration.
5.1 Should the power supply indicate that the weld head requires
calibration adjustment the calibration potentiometer can be accessed
at the bottom of the weld head, where the cable is attached. See
fig 5. Follow the instructions on your power supply in making
adjustments to the potentiometer. Repeat this procedure until the
power supply indicates that the head is calibrated.

Doc No. 7401236
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
5.0 ROTATION (SPEED) AUTO-CALIBRATION (Contd.)
Rotation calibration potentiometer.
Fig. 5
5.2 ROTATION (SPEED) MANUAL CALIBRATION
Some power supplies do not have auto calibration software. In this
case, the weld head motor is manually calibrated by creating a weld
program that should rotate the electrode 360 degrees. ie:1 RPM for a
total of 60 seconds, 2 RPM for a total of 30 seconds, 3 RPM for
a total of 20 seconds, etc. Select a speed (RPM) and corresponding
time close to or equal to the speed that you intend on welding at to
achieve the most accurate calibration.
5.3 The power supply must be in the “TEST” mode. Create a one level
weld schedule at your selected RPM. Amperage and pulse rate
settings may be set to any value, as during rotation calibration no arc
will be established. Set rotation mode to “CONT” (continuous rotation).
Set rotation delay and downslope times to 0.0.
5.4 Add one additional level with a duration of 5 or more seconds, with the
rotation mode set to “OFF”. This additional level (with rotation off) will
hold the electrode at its stopped position allowing the operator to see if
it traveled too far or not far enough.

Doc No. 7401237
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
ROTATION (SPEED) MANUAL CALIBRATION (cont’d.)
5.5 Be sure the power supply is in the “TEST” mode, and run the
program. Should the electrode rotate too fast (traveling more than 360
degrees), stopping beyond the home position, slow it down by turning
the potentiometer counter clockwise (CCW). Should the rotation be
too slow (rotating less than 360 degrees) stopping before it reaches a
full 360 degrees, turn the potentiometer clockwise (CW). Continue
this procedure until the electrode stops after 360 degrees of
travel.
6.0 CLAMP INSERT & GAS SEAL INSTALLATION
Clamp inserts are designed for a specific tube or pipe size. Select the
appropriate clamp for the specific tube or pipe to be welded. A set of clamps fits
one side of the weld head. Except for some special applications, or when using
the Model 8 with a gas seal on one side and a clamp on the other, two sets of
clamps are required. One set fits on each side of the head.
CAUTION
Use of the wrong size clamp, or clamping the head on the curved section of an
elbow or other irregular surface can result in damage to the clamp insert, weld
head clamp latch and/or hinge.
Note: A set of clamp inserts is made from one piece, and then split into two
halves. Each half is marked with matching alphanumeric characters.
Keeping matched sets together (on the same side of the weld head) will
result in the highest level of weld joint concentricity.
6.1 Before mounting the clamp insert into the head be sure both the
clamp and weld head clamp mounting groove are clean and free of
dirt, oil or other contaminants. The clamp mounting screw need only
be lightly snug.

Doc No. 7401238
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
6.0 CLAMP INSERT & GAS SEAL INSTALLATION (Contd.)
6.2 Some fittings and components do not have enough straight/round
surface for the weld head to grip with a clamp insert. However, orbital
welding is still sometimes practical by manual tack welding the two
components together first, and mounting a gas seal on the side of the
weld head where this fitting is to be positioned.
The hole in the gas seal is designed to be approximately 1/8” (3mm)
larger than the diameter of the fitting being welded, to allow shielding
gas to escape. Before welding, the gas seal must be positioned
around the fitting so the (1/16”) gap between the gas seal and the
fitting is somewhat uniform. See fig. 6
Fig. 6

Doc No. 7401239
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
7.0 ELECTRODE GEOMETRY & INSTALLATION
CAUTION
To prevent the possibility of electrical shock, the power supply must be in the
“TEST” mode before proceeding with electrode installation or removal. Take
extreme care that fingers or foreign objects are clear of the rotor when jogging.
The recommended electrode type is 2% Ceriated. (AWS Spec. A5.12/A5.12M,
Orange tip). This type of electrode provides superior arc starting and longer life
than 2% Thoriated electrodes. Other types can also be used. Consult factory for
recommendations.
The Model 8 series heads accommodate both 1/16” (1.6mm) or 3/32” (2.3mm)
diameter electrodes. The mounting holes in the rotor are approximately 180
degrees apart.
CAUTION
Do not install a 1/16” electrode into the 3/32” electrode mounting hole, and never
install more than one electrode.
7.1 The ceramic heat shield installed in the rotor is to be used in either the
1/16” or 3/32” electrode position. If it is mounted in the wrong location,
remove the two button head screws that hold the heat shield strap
and reattach it at the other electrode location. Be careful not to drop
the screws into the weld head.
7.2 The electrode length ultimately determines the arc gap, and the arc
gap determines the arc voltage which affects the heat input into the
weld. Thus a consistent arc gap from weld to weld is essential for weld
repeatability. In order to determine the electrode diameter, length and
tip diameter for a specific application, see figures 7 – 11.

Doc No. 74012310
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
7.0 ELECTRODE GEOMETRY & INSTALLATION (cont’d.)
Use this chart to determine the Rotor O.D.
Model Rotor O.D.
8-2000 3.452” (87.68mm)
8-4000 5.310” (134.87mm)
8-6625 8.094” (205.59mm)
Fig. 7
Use this chart to establish an appropriate Arc Gap and Electrode Tip diameter
Tube/Pipe Wall
Thickness
Recommended
Arc Gap
Recommended Tip
Diameter
0.020”–0.035” (.5 –1.0mm) 0.020”-0.030” (0.5-0.8mm) 0.010”-0.20” (.25-.50mm)
0.035”-0.085” (1.0-2.1mm) 0.050”-0.070” (1.3-1.8mm) 0.030” (0.8mm)
0.091”-0.154” (2.3-3.9mm) 0.070”-0.090” (1.8-2.3mm) 0.040” (1.0mm)
Fig. 8
Use the formula below along with your Rotor O.D. and Arc Gap to establish the
electrode length.
Fig. 9

Doc No. 74012311
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
7.0 ELECTRODE GEOMETRY & INSTALLATION (cont’d.)
Use this chart to determine the electrode diameter.
Tube/Pipe
Wall thickness
Electrode
Diameter
0.020” – 0.035” (.50 – 1.0mm) 0.040” or 1/16” (1.0 or 1.6mm)
0.049” – 0.083” (1.2 – 2.1mm) 1/16” (1.6mm)
0.091” – 0.154” (2.3 – 3.9mm) 3/32” (2.3mm)
Fig. 10
Fig. 11
7.3 Using the “JOG” button on the power supply or remote operators
pendant, jog the rotor around until the electrode (or electrode
mounting hole) is in the 12 o’clock position. See fig. 12.
7.4 Lay the weld head on its side to prevent accidental dropping of the
electrode into the weld head. Loosen the electrode set screw.

Doc No. 74012312
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
7.0 ELECTRODE GEOMETRY & INSTALLATION (cont’d.)
Fig. 12
Note: Be sure that the electrode mounting hole is free of foreign
matter in order for the electrode to be properly seated against
the electrode-stop roll pin.
7.3 Install the electrode from the rotor I.D. as shown in fig. 13. Tighten the
electrode set screw when the electrode is fully seated against the
electrode-stop roll pin. If the electrode is not fully seated against this
pin, the arc gap between the electrode and the tube will be incorrect.
Fig. 13

Doc No. 74012313
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
7.0 ELECTRODE GEOMETRY & INSTALLATION (cont’d.)
7.4 Spare electrode set screws are located in the weld head housing near
the cable attachment. See fig. 14.
Fig. 14
Spare electrode set screws.
8.0 SHIELDING GAS
The type of shielding gas used has a profound effect on the character of the arc
and the depth of weld penetration. The most commonly used shielding gas and
backup (I.D. purge) gas used is Argon. Gas mixtures of 95% Argon/5% Hydrogen
or 75% Helium/25% Argon are sometimes used to achieve deeper penetration.
Consult the factory for recommendations.
8.1 The Model 8 series weld heads work best when the arc gas is
set to the proper flow rate. Excessive flow rates can blow the arc, and
flow rates set too low can cause excessive weld oxidation
(discoloration) and electrode contamination. Use the manual purge
button on the power supply to open the arc gas solenoid, and set the
flow rate on your flow meter at your gas source.

Doc No. 74012314
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
8.0 SHIELDING GAS (cont’d.)
8.2 Prepurge time and post purge time are also a factor in minimizing weld
oxidation and electrode life. Refer to chart below for recommended arc
gas flow rates and minimum recommended pre & post purge times.
Note: The chart below (fig. 15) indicates the minimum recommended
purge times. Using longer purge times will extend the life of the
electrode and produce cleaner welds.
Model
Recommended
Arc Gas
Flow Rate (CFH)
Recommended
Minimum Pre/post
purge time (seconds)
8-2000 15 - 30 (7.0-14.1LPM) 30
8-4000 15 - 30 (7.0-14.1LPM) 30
8-6625 20 - 35 (9.4-16.5 LPM) 30
Fig. 15
Note: If the system is being hooked up for the first time, or if it has been a
number of hours since it was last used, it’s a good idea to initiate the
manual purge button on the power supply to clear the lines of
oxygen for a few minutes before initiating a weld sequence.
9.0 RETURN-TO-HOME (ROTOR) POSITION ADJUSTMENT
The Model 8 series weld heads will return the rotor to the “home” (open)
position at the end of the weld program, after the post purge time has timed-
out. A properly adjusted rotor will stop with both ends of the rotor flush or
slightly recessed in the housing. See fig. 16. A rotor that needs adjustment
will either stop with one side of the rotor protruding out from the housing, or
in a worst case, the rotor does not stop at all after it returns to home, in
which case, the power supply would have to be shut down before
attempting any adjustment.

Doc No. 74012315
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
9.0 RETURN-TO-HOME (ROTOR) POSITION ADJUSTMENT (cont’d.)
Fig. 16
Should your Model 8 require return-to-home adjustment, follow these steps:
9.1 Be sure the power supply is either turned off or in the “TEST” mode.
9.2 Remove the access plate. See fig. 17.
9.3 Loosen the screw that holds the bracket attached to the return –to-
home limit switch. See fig. 17.
9.4 Slide the limit switch bracket slightly toward the rotor, (to stop the rotor
sooner) or slightly away from the rotor (to stop the rotor later) and re-
tighten the bracket screw.
Fig. 17

Doc No. 74012316
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
9.0 RETURN-TO-HOME (ROTOR) POSITION ADJUSTMENT (cont’d.)
9.5 Turn on the unit, and open a weld schedule.
9.6 Be sure the machine is in the “TEST” mode, and be sure the rotor is
safe to rotate. No tools or fingers in the way. Touch “START”, then
immediately touch “STOP”. The rotor should return to the “HOME”
position. Should the rotor not stop in the correct “HOME” position,
repeat steps 9.3 – 9.6.
9.7 Replace the access plate.
10.0 CLEANING & MAINTENANCE
All of the connectors at the end of the cable must be kept clean and free of
grease, oil, dirt or other contaminants. Keep the cap on the electrical multi-
pin connector when not in use.
From time to time (depending on the cleanliness of the tube/pipe being
welded, the type and quality of the arc gas and the number of welds done)
the rotor and weld head housing will build up soot, which should be cleaned
on a regular basis.
10.1 Use isopropyl alcohol and Scotch Brite or steel wool to
clean the both brass (male and female) power and
ground connectors. Rinse off all debris and dry before using.
10.2 After cleaning the brass power and ground connectors, use a very
small amount of o-ring lube, oil or grease on the female (brass)
connector o-ring to facilitate easier connecting and disconnecting
10.3 Use a clean lint-free cloth and isopropyl alcohol to clean the rotor,
(black) rotor guide ring, weld head housing and view window.

Doc No. 74012317
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
11.0 STORAGE
If the weld head has been used with water-cooling, and is to be stored for
more than 1 month, the residual water or water/coolant mix should be
purged from the hoses and weld head to minimize internal corrosion.
This is also important if the weld head is to be stored where the
temperature might fall below freezing, as trapped water can freeze and
damage weld head and/or hose internals.
Although you may not be storing the adapter and /or extension cables,
leave them hooked up to the weld head when purging out the water.
11.1 To drain the coolant from the weld head and cables, use Arc
Machines, Inc. fitting part number 294-PB-06. Unplug the water
“supply” line from the cooling unit, (leaving the water “return” line
connected to the cooling unit) and attach the (female) fitting
(294-PB-06) to the disconnected “supply” line. See Fig. 18.
Fig. 18
11.2 Using a pressurized air source of maximum 20 PSI, (139 Kp)
(1.38 Bar) blow air into the fitting to force the water out of the cables
and weld head, and back into the cooling unit. See Fig. 18.
CAUTION, DO NOT USE AIR PRESSURE
ABOVE 20 PSI (139 Kp) (1.38 Bar)

Doc No. 74012318
MODEL 8 SERIES WELD HEAD
OPERATION MANUAL
11.0 STORAGE (cont’d.)
11.2 Attach the dust cap to the electrical connector, and store the weld
head in a clean, dust-free area.
11.3 Store the head with the clamp housing latches un-latched.