MHC

POWER STRAPPING HEAD

© Copyright 2006, Signode 512132 Rev. 4/2006

! This manual gives you information on SERVICING MACHINE
how to operate and maintain your
Signode MHC Power Strapping Head.

! Read and follow these instructions.

Failure to do this could result in severe
personal injury.

! Read and review application machine

manual. 1. Never service or oil moving machinery;
disconnect and lock out all power.

2. Remove packages from machine.

GENERAL CONSIDERATIONS
3. Follow the maintenance and service
1. Wear safety glasses
instructions in your manual.
with side shields
which conform to ANSI
Standard Z87.1 or EN 166.
SIGNS
2. Never put any part of your body into, or
near moving machinery. Never wear 1. Read all of the signs on machine.
loose clothing or jewelry.
2. Do not remove any signs from machine.
3. Inspect the machine for unsafe
conditions - DAILY - and replace all worn 3. Replace all missing or damaged signs.
or broken parts.

4. Keep work area uncluttered and well lit. ADDITIONAL CONSIDERATIONS

5. Only trained people are to operate and 1. To ensure proper operation of machine,
service machine. use the specified electric and/or air
power sources.
6. All covers and guards must be in place
before operating machine. 2. Do not overload machine by exceeding
Signode's recommended performance
7. Keep out of strap chute area while limitations.
machine is running.
3. Do not attempt to alter machine design
8. Additional safety instructions are located unless written approval is received from
throughout this manual. They serve to Signode.
warn the serviceman about potentially
hazardous situations. 4. Keep this manual at your machine. Refer
to it - often.

2
MACHINE DISCONNECT AND LOCK-OUT PROCEDURES
GENERAL CONSIDERATIONS JUNCTION BOX

This strapping head uses a centrally located

electrical junction box for routing and
connecting the power and control wiring.
Become familiar with the location, and Before servicing or removing any
operation of each shutoff device. connections disconnect and lockout all
power.
Disconnect/Lock-Out all power sources
before servicing machine.

Never use machine operating controls

as a means for locking out power. The electrical junction box does not have
a separate disconnect switch. Disconnect
and lockout all power supplies before
Lock out all electrical, pneumatic and servicing.
hydraulic supply systems which may be
connected to the machinery in which this
strapping head is installed. If the junction box must be serviced under
power, review the illustration below for the
Review the machine's application manual for various power connections. Please note some
specific lockout and disconnect devices. connections are both incoming and outgoing
power.
After locking out all supply power, allow
several minutes to pass before attempting to
work on this product. This time will allow for
any stored pneumatic and hydraulic power
to bleed down and for any electrical
capacitors to fully discharge.

3
TABLE OF CONTENTS
SECTION TOPIC PAGE

General Safety Instructions 2

Machine Disconnect & Lockout 3

SECTION 1 Introduction 1-1

Specifications 1-2
Major Components 1-3

Machine Adjustments:

Strap Width Guide 1-4

Strap Stop Guide 1-5

SECTION 2 Principles of Operation 2-1

SECTION 3 Head Maintenance:

Periodic Service Instructions 3-1

Weld Brush Replacement 3-2
Troubleshooting Guide 3-3

SECTION 4 Mechanical Assemblies:

Tension Module, 513400

· Bill of Material 4-2
· Assembly Reference 4-3
· Access Door 4-4
· Back Plate 4-5
· Feed Wheel 4-6
· Pivot 4-7
· Front Plate 4-8
· Pinch Wheel 4-9
· Drive Motor 4-10

Sealer Module, 513140

· Bill of Material 4-12
· Main View 4-13
· Anvil Pivot 4-14
· Gripper 4-15
· Platen 4-15
· Anvil 4-15
· Index Motor 4-15
· Electrical 4-16
· Separator 4-17

Recommended Spare Parts 4-19

4
INTRODUCTION
Because the MHC is typically installed into an application machine, specifications other than
those regarding this head will appear in the Application Machine Manual.

This manual will, however, guide and alert operating and service personnel with respect to safety,
operation and maintenance procedures for the MHC heads.

Most of the fasteners used in this machine are metric. Before removing and replacing
any part, refer to the Parts Listing to determine the proper tools to use and the correct
size hardware that may have to be replaced.

MHC TENSION MODULE

MHC SEALER MODULE

1-1
HEAD SPECIFICATIONS

ELECTRICAL: 230 Volts, 60 Cycles, 3 Phase

400 Volts, 50 Cycles, 3 Phase
460 Volts, 60 Cycles, 3 Phase

STRAP SIZE: 3/8" to 1/2"

RATE OF FEED: 12 feet per second (3.7 meters per second @ 60Hz)
10 feet per second (3.0 meters per second @ 50Hz)

RATE OF TAKE-UP: 12 feet per second (3.7 meters per second @ 60Hz)
10 feet per second (3.0 meters per second @ 50Hz)

STRAP TENSION: Variable from 25 lbs. to 200 lbs.

WEIGHT: Sealer Module: 22 lbs (10 kg)

Tension Module: 35 lbs (16 kg)

1-2
MAJOR COMPONENTS

1-3
STRAP WIDTH GUIDE
The strap guide which mounts to the
gripper cover is shimmed for optimum
machine performance. This guide is used
to keep the strap as straight as possible as
it travels through the sealer. Five shims are
used to adjust the strap path as needed to
improve feeding reliability or if changing
strap types. Use the instructions below to
modify shim configurations.

1. Remove the sealer cover by removing

the four socket head cap screws that
secure the cover to the sealer housing.

2. Release the spring tension from the anvil pivot assembly by unhooking the exposed end of the
extension spring from the pin mount in the gripper cover.

3. Pivot the anvil assembly backwards to expose the strap guide block, left-hand guide and
shims.

4. Remove the socket head cap screw that secures the guide block, left-hand guide and shims.
The components should easily slide off the alignment pin once the mounting screw has been
removed.

5. Re-orient the shim configuration as needed (see below) to improve strapping performance. All
five shims must be used. Wider strap configuration should have less shims behind the left-
hand guide and more in between the guide block. Narrow strap configuration should have
more shims behind the left-hand guide and less in between the guide block.

NARROW STRAP CONFIGURATION WIDER STRAP CONFIGURATION

NOTE: More than one adjustment may be necessary to achieve optimum performance. Do not
discard any of the five shims.

6. Reinstall the extension spring, sealer cover and mounting hardware.

1-4
STRAP STOP GUIDE
The strap stop guide that mounts to the anvil is shimmed
for optimum machine performance. This guide aids in
directing the strap through the sealer and prevents the lead
end of the strap of traveling too far upon re-entry. Multiple
shims are used to adjust the strap path as needed to
improve feeding reliability or if changing strap types. Spare
shims are kept under the head of the mounting screw for
future use. Use the instructions below to modify shim
configurations.

1. Remove the button head cap screw that secures the

strap stop guide. The guide should easily lift out from
the anvil once the mounting screw has been removed.

NOTE: The mounting screws also contains the spare

shims, use caution when removing the guide to not lose
any of the spare shims.

2. Add or remove shims from under the stop guide to adjust how deep the guide mounts in the
anvil. Heavier gauge strap configuration should have more shims under the guide to raise its
mounting position. Lighter gauge strap configuration should have less shims under the guide
to lower its mounting position.

LIGHTER GAUGE STRAP CONFIGURATION HEAVIER GAUGE STRAP CONFIGURATION

NOTE: More than one adjustment may be necessary to achieve optimum performance. Store
any extra shims not used under the head of the mounting screw.

3. Securely tighten the mounting screw to maintain the guide’s position.

1-5
1-6
PRINCIPLES OF OPERATION

GENERAL

The exact sequence of events of a strapping cycle depends, to a large degree, upon the
Application into which the MHC head has been placed. But, in general, plastic strap is fed through
the head and into a chute system. It re-enters the head, is drawn up around the load, welded and
cut from the supply. The completed tie is then released from the head in readiness for the next
cycle.

This Section will detail what events occur within the limits of the MHC head and will only allude to
what events occur elsewhere.

STRAP LOADING

Plastic strap, as supplied by the

dispenser, must be manually
inserted into the tension module
and loaded through the spring
loaded feed drive wheels and into
the guide system as follows:

1. Pull the pinch lever upward to

open the feed drive wheels.

2. Insert approximately 12” of strapping (with the natural curl facing

up) into one of the two available loading points. The MHC
tension module has an upper loading point (#1) and a lower
loading point (#2). Use the loading point most appropriate for
your application equipment.

3. Lower the pinch lever to securely contain the strap.

STRAP FEED

A start signal is then given and the feed and take-up module drive motor begins to rotate the drive
wheels in the feed direction. The feed wheels will continue to push the strap around the chute
until the lead end re-enters the head. To prevent the strap from being overfed, a proximity switch,
senses the stop position of the strap at the anvil. Once this switch senses that the strap has
completely fed around the chute and back into the anvil the feed & take-up drive is de-energized,
effectively stopping strap feed.

STRAP TAKE-UP

As the drive motor rotates, the drive wheels withdraw the strap from the chute and continue to
pull the strap tightly around the load or package. The larger drive wheel is driven by a mechanical
slip clutch. The smaller “gear driven” wheel acts as an idler at this stage and is forced to overrun
its drive shaft by use of a one-way roller clutch.

2-1
PRINCIPLES OF OPERATION, Continued

STRAP TENSION

At the same time, the index camshaft begins to rotate indexing the head from the feed position to
the Tension position, causing the following actions to occur:

During the indexing move from feed to tension, the end gripper extends to secure the lead-end of
the strap against the underside of the Anvil.

A reverse signal is sent to the feed and take-up module. The Drive Motor reverses direction
turning the drive wheels in the tension direction.

APPLIED TENSION

Once the strap has been pulled tight around the package the high-speed wheel begins to slip
(stall) on the mechanical slip clutch. At this point the smaller “gear driven” idler wheel is no longer
overrunning its drive shaft and now becomes the main drive wheel applying high tension to the
strap as set by the voltage which controls the electric clutch.

WELDING AND CUT-OFF

The feed and take-up drive motor is de-energized to release strap tension between the strap drive
wheels and the loop grip. This must be done before the strap supply is cut-off to avoid splitting
the strap lead end that may cause feed problems during the next cycle.

The index camshaft continues to turn advancing the head from the tension position to the loop
grip position.

The weld motor is turned on for a timed duration to allow time for the motor to approach proper
welding speed.

The loop grip continues to hold the tensioned strap against the underside of the Anvil. The index
camshaft continues to rotate which begins the advancement of the weld pad into the strap path.
As the weld pad advances the weld motor=s eccentric shaft, connected to the weld pad by an
eccentric arm, begins to move at a high rate of speed. Review Smart-Weld revolution settings
shown on the following page.

When the weld motor times-out, the index camshaft continues to rotate, moving the head from the
loop grip position to the weld-cool position.

Once the head has stopped in the weld-cool position, the following actions occur:

During the head's indexing from loop grip to weld-cool, the cutter blade extends and the strap
supply is cut-off. Then the rapidly moving weld pad contacts the strap pressing it against the
other, placing pressure on the two and beginning the welding process.

When the weld motor times out, the weld motor is turned off and the welding process is complete.

A weld cool timer is then activated. The weld cool timer controls the time during which the two
straps are held under pressure to allow the straps to properly fuse and cool.

2-2
STRAP RELEASE

Once the weld cool timer times-out, the index camshaft continues to rotate advancing the head
from the weld-cool position to the anvil open position.

When the head stops, the following actions occur:

During the head's indexing move from weld-cool to anvil open, the loop-grip, the end grip, the
cutter blade and the vibrator pad return to their neutral positions. The anvil retracts and the
welded tie is released to the load.

At this point in the cycle, the head will be delayed in this position.

FEED

When the above delay times-out, the index camshaft energizes advancing the head from the anvil
open position to the feed position.

When the head stops in the feed position, the following actions occur:

The anvil returns to the closed position and feed module is turned on. The feed and take-up drive
motor is turned on rotating the drive wheels in the feed direction for a set duration.

The MHC power strapping head is now ready for the next strapping cycle.

SMART WELD REVOLUTION SETTING

The purpose of the adjustable weld setting is to achieve the optimum joint as determined by the
specific application. Factors that affect joint quality are; strap type, voltage and frequency,
ambient temperate and cycle rate.

A visual inspection of a welded joint at initial machine set-up is sufficient for this setting. An
optimum amount of welded “flash” or “melt” protruding between the over-laid straps from at least
one side. Review the joints types below for comparison.

2-3
2-4
PERIODIC SERVICE INSTRUCTIONS

Wear safety glasses. Disconnect and lock out all power before proceeding.

Practice safe working habits when cleaning parts with compressed air.

Failure to follow the above could result in serious personal injury.

A regular maintenance program is essential for good service and long machine life. Listed below
is a suggested maintenance schedule for a machine receiving average use in an average
environment. When a machine is subjected to heavy use or used in a demanding environment
(excessive lint, dust, moisture, etc.) more frequent attention may be required.

DAILY

1. Blow all dust and debris from the strapping head, the strap chute and machine frame.

2. Open and clean outer strap guide on the tension module assembly.

3. Index the strapping head until the anvil opens. It is normal for particles of strapping to
accumulate in the weld/grip areas. These particles should be removed using moisture free
compressed air or a stiff brush.

4. Visually inspect a strap joint sample for full and proper bond with excess material protruding
on at least one side of the welded area.

BI-WEEKLY OR 10,000 TO 20,000 STRAP CYCLES

1. Index the head until the anvil opens and visually inspect the vibrator pad, welding linkage and
the cutter blade.

2. Visually inspect the entire head for loose or damaged parts.

3. Lubricate the eccentric arm assembly and the weld pad bearings with a high temperature
grease such as Accrolube or equivalent.

3-1
PERIODIC SERVICE INSTRUCTIONS, Continued

QUARTERLY OR 40,000 TO 60,000 STRAP CYCLES

1. Disassemble the welding module. Clean all parts with an approved solvent and relubricate
with a high temperature grease such as Accrolube or equivalent.

2. Check compression spring tension, proximity switch adjustments and camshaft timing.

3. Inspect all cam followers and camshaft for excessive wear.

4. Inspect weld motor brushes (P/N 439773). Replace brushes if less than 10mm long.

5. Inspect weld motor spade terminals (P/N 513391), replace if there are any signs of wear.

ANNUALLY OR 150,00 TO 200,000 STRAP CYCLES

1. Repeat the quarterly maintenance procedures.

2. Disassemble and clean the strapping head. Inspect and replace any worn or broken parts.

3. Check all electrical connections and retighten any which appear to be loose.

4. Replace the weld motor brushes and inspect the motor armature for wear.

5. After reassembling the strapping head run a few test cycles. Check for properly welded
strapping and make any necessary adjustments.

WELD MOTOR BRUSH REPLACEMENT (Part No. 439773)

To replace the brushes in the Weld Motor:

1. Access the Weld Motor by removing the Weld Motor Cover.

2. The brushes (2) are located at the end of the Weld Motor and are held in place against the rotor
(3) by a small compression spring attached to the brush. Brushes are secured in the motor by
a long spade terminal (4) on the end of each brush wire.

3. Using a small flat blade screwdriver, press

the release tab of the spade terminal to
remove it from the brush holder. The brush
can now be removed from the motor.

4. Replace the old brush assembly with a new

one. Compress the compression spring
and align the brush tabs with the
rectangular brush receptacle.

5. While continuing to hold the brush

assembly in place, slide the spade terminal
back into place until it locks in place.

6. Follow these instructions for the brush on

the opposing side of the motor.
3-2
TROUBLESHOOTING
The following items are the most common machine symptoms if problems should occur. For
symptoms or remedies not shown, contact Signode Engineered Products for additional
information and details. The following machine symptoms are shown in this manual:

#1 SYMPTOM: Machine will not feed strap.

#2 SYMPTOM: Head misfeeds on re-entry.
#3 SYMPTOM: Head will not index after strap feed.
#4 SYMPTOM: Head will not take-up after feed cycle.
#5 SYMPTOM: Head does not weld strap (vibrator motor not operating).
#6 SYMPTOM: Head does not weld strap (vibrator motor operational).
#7 SYMPTOM: Strap pulls out from head at end of take-up cycle.
#8 SYMPTOM: Strap pulls out from head at end of strapping cycle.
#9 SYMPTOM: Completed strap joint snags on anvil head.
#10 SYMPTOM: Head will not index to the weld position.

#1 SYMPTOM: Machine will not feed strap.

CAUSE REMEDY
1. Feed proximity switch not adjusted or 1. Inspect switch, adjust or replace if
not operating properly. necessary.

2. Inspect pinch roller spring, adjust or

2. Malfunctioning pinch roller spring. replace if broken.

3. Excessive dirt on feedwheels. 3. Clean all dirt and debris from wheels.

4. Strap path blocked. 4. Open guides, check and clean all strap
from path.

5. Feed proximity switch area blocked. 5. Clean area with compressed air and
remove any strap debris.

#2 SYMPTOM: Head misfeeds on re-entry.

CAUSE REMEDY
1. Burr or deformation on lead end of strap. 1. Cut off bad portion strap.

2. Worn or broken strap cutter. 2. Inspect strap cutter, replace if

necessary.
3. Burr or deformation on end gripper.
3. Inspect strap gripper, replace if
necessary.

3-3
TROUBLESHOOTING, Continued

#3 SYMPTOM: Head will not index after strap feed.

CAUSE REMEDY
1. PSM index proximity switch not 1. Inspect proximity switch for proper
operating. clearance of .002" to .020". Replace if
necessary.

2. Index camshaft not operating properly. 2. Inspect index camshaft for proper
operation, replace if necessary.
3. Broken or worn index camshaft motor.
3. Inspect condition of index motor. Replace
as needed.

#4 SYMPTOM: Head will not take-up after feed cycle.

CAUSE REMEDY
1. Feed proximity switch not proper set or 1. Inspect switch for proper clearance of
broken. .002" to .020". Replace if necessary.

2. Lead end of strap not activating switch. 2. Check strap path for obstructions.

#5 SYMPTOM: Head does not weld strap (weld motor not operating).
CAUSE REMEDY
1. Low or no input voltage at motor. 1. Inspect machine wiring and supply
voltages.

2. Worn or broken motor brushes. 2. Inspect motor brushes, replace if

necessary.

3. Bad motor winding. 3. Inspect motor winding for possible

defects, replace if necessary.

#6 SYMPTOM: Head does not weld strap (vibrator motor operational).

CAUSE REMEDY
1. Oil on strapping. 1. Clean all oil away from potential areas of
strap contact within entire machine.
2. Weld eccentric bearing or shaft worn. 2. Replace both the bearing and shaft.
3. Weld pad or cage bearings worn. 3. Replace weld pad and cage bearings as
necessary.

3-4
#7 SYMPTOM: Strap pulls out from head at end of take-up cycle.
CAUSE REMEDY

1. End gripper not holding strap. 1. Replace end gripper compression spring.

2. End gripper (and/or pins) worn. 2. Replace the end gripper.

#8 SYMPTOM: Strap pulls out from head at end of strapping cycle.

CAUSE REMEDY
Malfunctioning strap dispenser. Check dispenser adjustments for proper
operation.

#9 SYMPTOM: Completed strap joint snags on anvil head.

CAUSE REMEDY
1. Anvil pivot pin broken or worn. 1. Replace pivot pin.

2. Cam follower worn. 2. Replace the cam follower bearing.

3. Anvil cam follower worn, not opening 3. Replace the cam follower.
anvil wide enough.

#10 SYMPTOM: Head will not index to the weld position.

CAUSE REMEDY
1. Feed wheels slipping on strap. 1. Inspect pinch roller spring, adjust or
replace if broken.

2. Index camshaft not indexing when 2. Check index motor for proper operation.
signaled. Replace if necessary.

3. Index proximity switch not sensing target. 3. Inspect proximity switch for proper
clearance of .002" to .020". Replace if
necessary.

3-5
3-6