Knife SharpeningKnife Sharpening

Sheldon Becker Southern Qld Institute of TAFE

Poultry Processing

Using knives continuously relates up to 50% of injuries (lacerations or muscle strains)

Meat processing

In the red meat industry up to 68% of injuries

Of which 32% is cuts &lacerations

Blunt Knives

- are frustrating to use

- can lower the quality of the product

- often the cause of accidents

- can be responsible for Occupational Overuse Syndrome (OCC) type injuries

Who likes sharpening knives?

Blunt knives can lead to unsafe practices

Poor running point – Running hand up blade

Pushing when blunt – Physically pushing and dragging the knife

Over stretching – Not maintaining balance properly, not keeping up

Violent or sudden movements – Stabbing or hacking at the product

Deterioration – Tiredness, hands and arms are can cramp up & get sore

Emotional and Physical well being – Facing another day with a blunt knife is not fun, social issues impacting on your work

Incorrect steeling practices – Back steeling, uneven angles, not checking steeling action, grip on knife, and steel is incorrect

Repetition work – Continuously making additional cuts or doing same task

How have most people here How have most people here learnt how to sharpen a knife?learnt how to sharpen a knife?

Maybe from a fellow workerMaybe from a fellow worker

Some workplaces have a mentor/ trainerSome workplaces have a mentor/ trainer

Watching others sharpen their knivesWatching others sharpen their knives

Taught themselves through trail and errorTaught themselves through trail and error

Benefits of Knife Sharpening trainingBenefits of Knife Sharpening training

Would see a reduction in:

Knife related injuriesTendonitisCarpel TunnelTennis ElbowMusculoskeletal injuriesTime off workImproved productionJob becomes easier

TrainingWho to start with:

staff new to the plant or industry

all staff demonstrating poor technique

staff with high incidents of knife injuries

staff struggling with the job

staff open to change

Key points to lessen knife injuries

Warm up before starting

– Follow recommended stretching practices. Use a good shape blade

– Choose the correct knife for the job. Work with a rhythm

– Minimise your blows or cuts and work more efficiently

Take breaks

– Do not work through breaks

- Take breaks as required

Identifying the symptoms of musculoskeletal injuries

Muscle discomfort Fatigue Aches and pains Soreness Hot feelings Cold feelings Muscle tightness Numbness tingling Muscle weakness

Occupational Overuse Syndrome (OOS)

OOS usually develops over a

period of time. Caused or aggravated by :-

- sustained or constrained postures - repetitive movements

One explanations for OOS is that it is caused by the muscles being held too tight for long periods of time

NZ Grip force studyIndependent study found

20% of the process workers have a reasonably good knife

40% had an average knife

40% had a knife that was insufficient for the task

NZ Grip force study

Study also found the tighter the grip on the

knife the less blood flow in the hand and arm.

The size of the hand holding the knife is also a factor on grip force.

The knife lengthThe length and weight test used to determine grip forcePlace a 0.5 kg weight 13 cm, 15 cm, 17 cm distances along the steel or bar.

The grip force has increased as the length of each knife increases.

Longer blades require a greater grip force than shorter blades.

Cutting Force

A sharp knife requires 30% less force to cut than an average knife

A sharp knife also enables a task to be performed 30% faster, and requires 30% less grip force

A processing room with consistently sharp knives produced a 1 to 3 % greater yield than the same room with normal levels of sharpness

By testing a knife we can now tell how much cutting force is required to cut with that knife

We can now calculate how much cutting force a worker is using over a days work

Sharpness Tester

Score

Example A worker boning forequarters all day would use

approx 6400 cutting strokes a day

A sharp knife has a cutting force of 1.1kg per cutting stroke

1.1kg x 6400 strokes = 7.40 tons of daily force

If we multiply 6400 strokes with a 15kg blunt knife, we end up with a daily force of 96 ton

This equates to 88.6 tons more cutting force than a sharp knife

NZ experience

Photo courtesy of Anago Ltd

Equipment use to sharpen and maintain knives

Knives and their correct storage equipment

PPE (cut resistant gloves, safety glasses)

Grinding wheels (grinders)

Sharpening stones Steels

Washing & sterilising facilities

Safety Equipment used

when sharpening a knife

Cut resistant Safety glasses

Choose a knife suitable for the task.

Skinning Knife

Curved boning knife

Slicing knife

Straight boning knife

Knife Shapes

FlatConvex Hollow Concave

Equipment used to shape/sharpen

knives

Sandstone wheel Belt Grinders

Grinding the knife

Sharpening the knife

Sharpening or honing stone are used to

establish a sharp edge on a knife.

Methods used to sharpen a knife

Sharpening stone Setter

Issues Evenly grinding of knives to the correct shape

- both sides

- from tip to heel

Evenly sharpening knives (correct edge)

- both sides

- from tip to heel

Evenly & effectively steeling knives

“It all about the correct angles”

Hollow Grinders

Used by authorised personal only

Knife setter

Knife setters

Creating a feather

Work from tip to heel, then heel to tipto develop a feather. Turn knife over & repeat process

Stand on handle side of knife when stoning. Place thumb and forefinger on stoning rod & other hand on stoning bar.

Removing feather

Start by placing heel of stone on the knife tip. Pull the stoning rod straight back over the cutting edge overlapping the stone on each stroke.Turn knife over & repeat

Run the knife through a plastic block (Feathering Block)

Finishing strokes

Place the heel of the stone on the tip of the knife and pull stoning rod back toward the knife handle 6 times.Turn knife over and repeat process

Steeling a knife

To remove any burrs from the edge

To straighten (centre) the edge

Types of Steels

Holding a knife

Make sure the knife butt sits in the groove of your thumb and forefinger palm

Make sure you tuck your little finger on the side of the handle

The knife should be in astraight line with your arm

Steeling a knife

Hold steel as above with the thumb tucked behind steel

Check arm, steel and knife are square and in line.Knife handle centre of wrist

Storing Knives

Knives must be stored in the pouch when not in use

Testing biteTesting bite

Bite Stick Stick

Bites left Bites right

Both sides of the knife are sharp

Testing biteTesting bite

Bite Stick Stick

Slides rightBites left

Bite left only knife is turned to the leftSteel left side of knife the bite side.

Testing biteTesting bite

Bite Stick Stick

Slides left

Bite right only knife is turned to the rightSteel right side of knife the bite side

Bites right

Testing biteTesting bite

Bite Stick Stick

Slides left Slides right

Slides both ways, there is no bite, knife willneed to be steeled again or sharpened

Safety Equipment

when using a knife

Cut resistant

Mesh

Safety Aprons

Now That’s A Knife

AcknowledgementsAcknowledgements

Southern Qld Institute of TAFE would like to Southern Qld Institute of TAFE would like to acknowledge contributions by:-acknowledge contributions by:-

Big Bay Skills Training LtdBig Bay Skills Training Ltd

Argus Realcold LimitedArgus Realcold Limited

Teys Bros Pty LtdTeys Bros Pty Ltd

Question?Question?

ThankyouThankyou