Carding Machines

GUARDING

of

CARDING MACHINES

Published by

Occupational Safety and Health

A Service of the Department of Labour

ISBN 0-477-03442 -X

Important Note:

All the publications in the Publications Archivecontain the best guidance available at the time ofpublishing. However, you should consider the

effect of any changes to the law since then.You should also check that the Standards referred to

are still current.

CONTENTS

Introduction 4

Background and Future Developments 5

Hazards 7

Legal Requirements 8

Guarding Requirements 9

Woollen carding machine 9

Worsted carding machine 11

Guard Construction 12

Material 12

Type 12

Support 12

Deadlock/Padlock System 17

Trapped Key Interlock System 21

Solenoid-Operated Bolt System 24

Appendices (photographs)

Sliding panel guards with trapped

key interlock on a carding machine 27

Hinged panel guards with trappedkey interlock on a carding machine 28

Fixed guards with hinged panel

doors locked by solenoid bolt 29

Further Information 30

4 Guarding of Carding Machines

ARCHIVEINTRODUCTION

This booklet sets minimum requirements for theguarding of carding machines in order to establish a

uniform guarding standard in the industry. It hasbeen discussed and agreed with the industry. The

Department of Labour requires all owners of cardingmachines, whether they are in the woollen industriesor own non-woven machinery, to comply with these

requirements.

Guidelines are given on different systems of lockingand interlocking the guard panels, which have been

implemented successfully by some owners of cardingmachines. As a guide, technical outlines are also

included to assist machine owners to upgrade andinterlock guards for their machines.

Carding machines are used in both worsted and

woollen yarn production. They are also used in theproduction of most other staple yarns. In all cases,the design of the carding machine is arranged to suit

the product to be carded, but the basic principle ofguarding these machines is the same.

The principles and examples given in this booklet do

not exhaust all the possibilities. Any other system ofguarding which is equally effective or better will beacceptable to the Department of Labour.

Guarding of Carding Machines 5

ARCHIVEBACKGROUND AND FUTURE

DEVELOPMENTS

The requirements for guarding of carding machines,

developed many years ago, were that sliding gates orhinged panels should be provided to enclose the

perimeter of the machine. There was no demand forlocking or interlocking of the guards.

However, accident statistics for carding machines in

recent years have proved that the provision of slidingor hinged guards without any locking system is inad-equate to prevent accidents on these machines. This

is mainly due to the fact that operators can easilygain access to moving parts of the machine without

isolating the machine first, or waiting until the over-run has completed. Guards can also be left openduring operation and therefore defeat their purpose.

This does not strictly comply with the requirements ofsections 15, 16 and 17 of the Machinery Act 1950.

The objective of the Department of Labour and the

industry is to improve the guarding standards ofcarding machines, to ensure a safe working environ-

ment, and to minimise loss of production and costsdue to accidents. A number of firms have developedand implemented different approaches to lock or

interlock their guards by the following systems:

• Guards are locked by padlocks and keys heldby a responsible person.

• Guards are interlocked to the motion of the

machine by a trapped key interlock systemincorporated with a time delay unit.

• Guards are interlocked to the motion of the

machine by a solenoid-operated bolt system,which will only release the locking bolts when a


ARCHIVErotation-sensing device has detected that themachine is at a complete standstill.

The department’s requirements for guarding of card-

ing machines are that the perimeter of the machineshall be enclosed by barrier guards of appropriateheight to prevent reach to dangerous parts, with

restricted access allowed through sliding or hingedgates. These gates shall be locked by padlocks or

deadlocks and the keys held by a responsible person.

The use of padlocks or deadlocks to lock guards willbe effective only in firms which have:

• A good record of training and supervision of

personnel.

• Restricted access for unauthorised personnel tothe machine.

Whenever possible, it is strongly recommended that

carding machine owners interlock their guards, inorder to eliminate the possibility of accidents.


ARCHIVEHAZARDS

A carding machine consists of a large number oftransmissions, rollers, belts, pulleys, chains and gear

wheels. It can be very dangerous if not adequatelyguarded. Fingers, hands, feet or loose clothing can

easily get caught between the in-running nips andtrapping points created by moving parts of themachine and cause severe injuries like fractures,

amputation or even death.

The main areas of hazards are:

• The in-running nips and trapping points at thetransmission and rollers which have overrun

after the power has been isolated.

• At the tape condenser of a woollen cardingmachine, as broken threads have to be put

back on the appropriate tapes where there arenip hazards with the machine running.

• Around the scotch feed or broad band area,

where there are some transmission andtrapping hazards between moving and

stationary parts.


ARCHIVELEGAL REQUIREMENTS

Sections 15, 16 and 17 of the Machinery Act 1950require moving parts of any prime movers, every part

of transmission machinery and every dangerous partof any machinery to be securely fenced, unless parts

are in such a position or of such construction as to besafe to every person employed or working on thepremises, as they would be if securely fenced.

These requirements can be met in respect of cardingmachines by:

• Complete enclosure of the moving parts of theprime mover transmission by means of barrier

guards, with restricted access allowed throughsliding or hinged gates which are locked or

interlocked. This includes shafts, belts, pulleys,rollers and all other transmission components,

unless they are beyond reach by any person.

• Secure fencing of all dangerous parts toprevent access while they are in motion.


ARCHIVEGUARDING REQUIREMENTS

Woollen carding machine

A woollen carding machine has three parts: the firstis the scribbler, the second is the intermediate scrib-bler (broad band or scotch feed) and the third is the

carder or condenser card.

Scribbler

This area is to be enclosed by barrier guards of

appropriate height, with restricted access allowedthrough sliding or hinged gates which are locked or

interlocked to the motion of the machine.

Scotch feed or broad band

This area can be left as a walk-through area, but all

the transmission and trapping hazards associatedwith the overhead lattice and traversing carriage areto be guarded. Scotch feed or broad band transmis-

sions are to be enclosed if they are within reach. Alldangerous parts within reach are to be guarded

locally or by means of barrier guards.

Carder

The sides of the carding section and the condenser

are to be enclosed by barrier guards of appropriateheight, with restricted access allowed through slidingor hinged gates which are locked, or interlocked, to

the motion of the machines.

Condenser

If it is necessary to repair the wool threads at the top

of the tape condenser while the machine is in motion,an access ladder and a walkway with proper hand-

rails and platforms are to be constructed across this


ARCHIVEarea to enable the operator to carry out work safely.The transmission and dangerous parts at each side ofthe rollers at the condenser section must be enclosed

by guards if they are within reach during access tothe top of the condenser. This is to apply even when

gates are fitted to this area.

An air tool or a stick must be used to repair the woolthread. Using hands for such a task is prohibited.

A trip wire or bar or similar device shall be provided

in the area at a readily accessible location, for stop-ping the machine in the event of an emergency.

When gates near the condenser area are open, access

to other parts of the carder must be blocked off, sothat the operator cannot use these gates for access toan area other than the tape condenser area.

For interlock gates, access to the condenser can be

controlled by provision of a separate lockable gate tothis area, with the key held by a responsible person

other than the operator. If the trapped key interlocksystem is used, this provision may not be necessary.

A spare key can be held by the responsible person foroverriding the interlock to allow access for the pur-pose of repairing wool thread at the condenser while

the machine is in motion.

The entry gate to the pit to the rear of the condensermust also be locked or interlocked. Access to the

bottom of the condenser area for repairing woolthread shall also be controlled in the same way asrequired at the top of the condenser.

The transmission and dangerous parts at each side ofthe condenser tape rollers which are within reachshall be guarded as far as is practicable.

A trip wire or bar or similar device for stopping the

machine during an emergency shall also be fitted inthis area where repairing of wool thread is required.


ARCHIVEThe underside of the carder must be fenced off toprevent the operator from going beyond the con-denser area. A gate, which can be locked or inter-

locked, shall be provided to limit access to areasbeyond the condenser area.

Machine adjustment

Where possible, machine adjustments are to be madewith the machine stopped. Any adjustment to the

machine which is necessary while the machine is inoperation, shall, where practicable, be carried outwith the guards in position. Where it is not practica-

ble for the guards to be in position while adjustmentis made to the machine in motion, only a responsible

person like a supervisor or carding engineer mayhave access to the area, and then only while thenecessary adjustments are being made.

Worsted carding machine

The worsted carding machine has only one part and

is therefore about half the length of a woollen cardingmachine, or smaller. The guarding of the worstedcarding machine shall meet the relevant require-

ments for the woollen carding machine.


ARCHIVEGUARD CONSTRUCTION

Material

The barrier guard must be soundly constructed ofsuitable materials, which can be solid or perforated.The perforation or the mesh wire shall be such that

fingers cannot reach the dangerous parts.

Mesh sizes and minimum distance between a guardand a dangerous part can be established from the

department’s booklet The Ergonomics of MachineGuarding.

Where a guard made of sheet metal or mesh would

obstruct visibility of areas required to be under obser-vation during the operation, a screen of shatter-resistant transparent material made, for example, of

toughened glass or Perspex, should be provided.

Type

If there is a constraint of space between machines,

sliding panels are appropriate for access throughguards along the sides of the machine. Guards with

hinged panels for access or contour guards usuallyoccupy more space and, hence, they are to be usedonly where there is ample space between machines.

In this case, the number of gates can be reduced byinstalling the fixed barrier guards along the sides of

the machine, with hinged panels at each corner foraccess. Figures 1, 2 and 3 show the different types ofguarding used for carding machines.

Support

Guards must be securely fixed to independent sup-ports or to the machine frame. They are to be of suffi-

cient strength to prevent deflection which would allowaccess to the dangerous parts. The sliding type


ARCHIVEshould be hung from overhead tracks and fitted with

bottom rails to ensure stability and smooth sliding of

the gates.

Where necessary, there can be clearance under theguards for cleaning purposes, provided this clearance

does not allow reach to the danger zone.

Openings, clearances and gaps in guards must notexceed those as determined from the booklet The

Ergonomics of Machine Guarding.


ARCHIVE

Figure 1. Guards with sliding panels

(b) Carder Gate within interlock sliding

panel for access to condenser

and locked by deadlock


ARCHIVE

Figure 2. Guards with hinged panels

(a) Scribbler

(b) Carder


ARCHIVE

Figure 3a. Fixed guards at sides with hinged door at each corner

Figure 3b. Contour guard


ARCHIVEDEADLOCK/PADLOCK SYSTEM

To prevent guards from being left open during opera-tion, it is essential that all gates for access to the

moving parts of the machine shall be locked by dead-locks or padlocks. Locks must be of robust construc-

tion and keys held by a responsible person (the fore-man or plant manager) and, if necessary, this respon-sibility can be shared between two persons other

than the operator.

The person in charge of keys must ensure that themachine power has been isolated and the machine

overrun has completed, before he unlocks any lock.

A convenient and cost-effective way of locking gates,which will also minimise human error, is by locking a

series of panels for:

• Sliding gates by means of a long pipe or rodfitted with bars or pins, which slot into holes in

panels and lock them together by using onelock at the end of the rod, as shown in figure 4.

• Hinged gates by using a long bar which can

hinge down when all gates are closed, andlocked by a deadlock at the end of the bar, asshown in figure 5. Gates shall be designed to

prevent the locking bar from hinging downwhen any gate is open. Stops must be fitted to

prevent gates from being pushed inward.

In both cases, the locking rod or bar and componentsshall be of robust construction, with sufficientstrength to withstand any external force likely to be

imposed on them.

If systems as illustrated in figures 4 and 5 are usedfor locking gates, a normally closed limit switch can

be fitted at the end of the locking rod or plate, toensure that the machine cannot be started, unless all


ARCHIVEthe gates are shut. Where guards are of the hingedpanel type, a photoelectric light beam can also beinstalled to detect whether gates are shut. If one gate

is opened, the light beam will be interrupted and themachine cannot be switched on.


ARCHIVE

Figure 4. A series of sliding panels locked by a rod fitted with pins

which slot into holes in the panels

Round with hole for lock bolt is

fitted to the rid or pipe

Deadlock or interlock deadlock

Turning lever

for locking

and unlocking

of panels

Pin slots into hole and

locks panel

Rod or pipe

Sliding panel

(a) Gate for access to condenser

and locks by a deadlock (for

interlock system only)

(b)


ARCHIVE

Figure 5. A series of hinged panels locked by a hinged bar with a

deadlock at one end

Locking bar at open position

Deadlock or interlock

deadlock at locking

position

Locking bar

attached to

circular plate

Circular plate for locking

(a)

(b)


ARCHIVETRAPPED KEY INTERLOCK SYSTEM

The sliding or hinged gates can be interlocked to themotion of the machine by using a trapped key inter-

lock (key exchange) system, which works on theprinciple that the master key, which controls the

power supply to the machine through a switch at themaster key box, has to be turned off before keys forindividual guards can be released.

A typical trapped key interlock system is illustrated infigure 6. When the machine is operating, key A istrapped in the power supply interlock and all access

points are locked closed.

A time delay unit or a rotation-sensing unit can beused to monitor the residual motion or overrun of the

machine after the power has been switched off.

To open the access gates, the steps are:

• Power is isolated and key A can be released.

• Key A is inserted and kept captive in the time

delay unit (or rotation-sensing unit).

• The unit ensures that there is a specific time

interval which has to be greater than the timeof overrun (or the unit detects that the motionin the machine has stopped) before key B is

released.

• Key B is inserted in the key exchange box andkept captive.

• Key C can then be released for opening gates

and kept captive in each lock.

Only by reversing this key transfer sequence cannormal operation of the machine resume.

Instead of locking each individual gate by a lock, the

system of locking a series of gates together by using


ARCHIVEone lock, as mentioned previously and shown infigures 4 and 5, is recommended. This will reducethe number of keys in the key exchange box and

hence reduce the time for locking and unlocking. Italso significantly reduces the cost of installation.

A small individual gate can be provided at the guard

near the condenser, to control access to the top of thecondenser for repairing wool threads, if necessary,

during machine operation. This gate can be locked byan ordinary deadlock and opened only by aresponsible person other than the operator.

This interlock-based safety control system is a con-

venient and cost-effective way of eliminating humanerror and providing positive protection for person and

machine.


ARCHIVE

Figure 6. Diagrammatic arrangement of a trapped key interlock

system

Machine Power Supply

ON-key trapped LOCKED OFF - key free

Rotation-sensing

or time delay unit

Access keys locked -

Key B freeAccess keys released -Key B trapped

Access gateslocked

Access gatesopen - keys

trapped

Machine running Machine stopped


ARCHIVESOLENOID-OPERATED BOLT SYSTEM

The solenoid-operated bolt system, which incorpo-rates a rotation-sensing device or a time delay unit, is

another method of interlocking gate guards.

Each gate is locked by means of an interlock dead-lock, fitted with a solenoid to prevent withdrawal of

the lock bolt until an electrical signal is received fromthe rotation sensing or time delay unit. To open gates,

the following sequences are followed:

• First motion of the key in the power control boxswitches off the power to the machine.

• The rotation-sensing unit detects that the

machine is completely at a standstill or thetime delay unit monitoring the time is at theend of the predetermined period.

• Key can then be turned to the second positionand solenoids activated.

• Lock bolts are withdrawn and gates are opened.

Normally closed limit switches shall be fitted to gates

so that the solenoid cannot be activated to lock thebolt unless all gates are closed. When the solenoid-operated bolts have locked all gates, an electrical

signal is transmitted to the power control box and themachine can be switched on.

Electrical limit switches used for guard interlocking

shall be arranged so that the actuator is releasedwhen the guard is fully closed allowing the machineto start. When the gate is opened the switch contacts

are positively opened by the cam and the machinecannot be started.

Details of this preferred method of fitting limit

switches are set out in the department’s bookletElectrical Interlocking of Machinery Guards. These are


ARCHIVEalso shown in figure 7 for hinged gates and figure 8for sliding gates.

Gates shall be constructed in such a way or fitted

with a device to prevent them from being shut unin-tentionally. For this purpose, a spring may be used toact against the closing of a gate. A latch which is

operated manually can be used to hold the gate inposition temporarily, so that the solenoid-operated

lock bolt can be engaged.


ARCHIVE

Figure 7. Normally closed limit switch used for hinged gate

Figure 8. Mounting of limit switches for sliding gates

Sliding

gate closed

Sliding

gate open

(a) INCORRECT

(a) CORRECT

Sliding

gate closed

Sliding

gate open

(a) Gate open (a) Gate closed


ARCHIVEAPPENDIX 1: SLIDING PANEL GUARDS WITH

TRAPPED KEY INTERLOCK ON A CARDING

MACHINE

(Photographs courtesy of Feltex Carpets of New Zealand)


ARCHIVEAPPENDIX 2: HINGED PANEL GUARDS WITH

TRAPPED KEY INTERLOCK ON A CARDING

MACHINE

(Photographs courtesy of UEB Carding Ltd.)


ARCHIVEAPPENDIX 3: FIXED GUARDS WITH HINGED

PANEL DOORS LOCKED BY SOLENOID BOLT

(Photograph courtesy of Capston Printing Works Ltd.)


ARCHIVEFURTHER INFORMATION

Further information on guarding of carding machinesand other machinery can be obtained from your

nearest Department of Labour, Occupational Safetyand Health area office.

Offices are located at:

Whangarei New Plymouth

North Harbour Napier

Penrose Lower Hutt

West Auckland Wellington

Manukau Nelson

Rotorua Christchurch

Tauranga Dunedin

Palmerston North Invercargill

Documents

Carding Machines