Knife 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 Who likes sharpening 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 learnt how to sharpen a knife? Maybe from a fellow worker Some workplaces have a mentor/ trainer Watching others sharpen their knives Taught themselves through trail and error

Benefits of Knife Sharpening training Would see a reduction in: Knife related injuries Tendonitis Carpel Tunnel Tennis Elbow Musculoskeletal injuries Time off work Improved production Job becomes easier

Training Who 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 study Independent 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 length The length and weight test used to determine grip force Place 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

when sharpening a knife Safety Equipment used when sharpening a knife Cut resistant Safety glasses

Choose a knife suitable for the task. Skinning Knife Curved boning knife Straight boning knife Slicing knife

Knife Shapes Convex Flat 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) Evenly & effectively steeling knives “It all about the correct angles”

Hollow Grinders Used by authorised personal only

Knife setter

Knife setters

Creating a feather Stand on handle side of knife when stoning. Place thumb and forefinger on stoning rod & other hand on stoning bar. Work from tip to heel, then heel to tip to develop a feather. Turn knife over & repeat process

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 a straight line with your arm

Steeling a knife Check arm, steel and knife are square and in line. Knife handle centre of wrist Hold steel as above with the thumb tucked behind steel

Storing Knives Knives must be stored in the pouch when not in use

Testing bite Bites left Bites right Bite Stick Stick Both sides of the knife are sharp

Testing bite Bites left Slides right Bite Stick Stick Bite left only knife is turned to the left Steel left side of knife the bite side.

Testing bite Slides left Bites right Bite Stick Stick Bite right only knife is turned to the right Steel right side of knife the bite side

Testing bite Slides right Slides left Bite Stick Stick Slides both ways, there is no bite, knife will need to be steeled again or sharpened

Safety Equipment when using a knife Cut resistant Mesh

Safety Aprons

Now That’s A Knife

Acknowledgements Southern Qld Institute of TAFE would like to acknowledge contributions by:- Big Bay Skills Training Ltd Argus Realcold Limited Teys Bros Pty Ltd

Question? Thankyou