materials handling

Material Handling

Material handling is the function of moving the right material to the right place in the right time, in the right amount, in sequence, and in the right condition to minimize production cost. The cost of MH estimates 20-25 % of total

manufacturing labor cost in the United States [The Material Handling Industry of America (MHIA)]

Material Handling Objectives

A. Reduce Unit Material Handling CostEliminate Unnecessary HandlingHandle Material in Batch LotsMinimize Required Handling TimeReplace Handling Equipment as Appropriate B. Reduce Production TimeMinimize Delays of Machine OperationsMaintain Uniform, Appropriate Movement of

MaterialUse Automatic Processing When Appropriate

Material Handling Objectives

C. Reduce OverheadMinimize Non-Productive LaborPrevent Damage to MaterialsCoordinate All Material Handling Systems

D.    Conserve Floor SpaceAvoid Excessive Stock StorageMove Materials in a Position to Save SpaceUse Equipment Requiring No Floor Space E.     Prevent AccidentsReduce Physical Load RequiredInsure Handling Equipment is Safe F.      Improve Employee MoraleProvide Proper Relationship Between Employee & Work

The primary goal is to reduce unit costs of production

Maintain or improve product quality, reduce damage of materials

Promote safety and improve working conditions Promote productivity

material should flow in a straight line use gravity! It is free power move more material at one time mechanize material handling automate material handling

Promote increased use of facilities Reduce tare weight (dead weight) Control inventory

Material handling equipment includes: Transport Equipment: industrial trucks,

Automated Guided vehicles (AGVs), monorails, conveyors, cranes and hoists.

Storage Systems: bulk storage, rack systems, shelving and bins, drawer storage, automated storage systems.

Unitizing Equipment: palletizers Identification and Tracking systems

1. Material Characteristics

Category Measures

Physical state

Size

Weight

Shape

Condition

Safety risk and risk of damage

Solid, liquid, or gas

Volume; length, width, height

Weight per piece, weight per unit volume

Long and flat, round, square, etc.

Hot, cold, wet, etc.

Explosive, flammable, toxic; fragile, etc.

2. Flow rate

Manual handlingHand trucks

Powered trucksUnit load AGV

Conveyors ConveyorsAGV trainHigh

Low

LongShort Move Distance

Quantity of material moved

3. Plant LayoutLayout Type Characteristics Typical MH Equipment

Fixed – position

Process

Product

Large product size, low production rate

Variation in product and processing, low and medium production rates

Limited product variety, high production rate

Cranes, hoists, industrial trucks

Hand trucks, forklift trucks, AGVs

Conveyors for product flow, trucks to deliver components to stations.

1. The Planning Principle Large-scale material handling projects usually

require a team approach. Material handling planning considers every

move, every storage need, and any delay in order to minimize production costs.

The plan should reflect the strategic objectives of the organization as well as the more immediate needs.

Principles of Material Handling

2. The systems principle: MH and storage activities should be fully integrated to form a coordinated, operational system that spans receiving, inspection, storage, production, assembly, …, shipping, and the handling of returns. Information flow and physical material flow

should be integrated and treated as concurrent activities.

Methods should be provided for easily identifying materials and products, for determining their location and status within facilities and within the supply chain.

3. Simplification principle simplify handling by reducing, eliminating,

or combining unnecessary movement and/or equipment.

Four questions to ask to simplify any job: Can this job be eliminated? If we can’t eliminate, can we combine

movements to reduce cost? (unit load concept)

If we can’t eliminate or combine, can we rearrange the operations to reduce the travel distance?

If we can’t do any of the above, can we simplify?

4. Gravity principle Utilize gravity to move material whenever

practical.

5. Space utilization principle The better we use our building cube, the

less space we need to buy or rent. Racks, mezzanines, and overhead

conveyors are a few examples that promote this goal.

6. Unit load principle Unit loads should be appropriately sized

and configured at each stage of the supply chain.

The most common unit load is the pallet cardboard pallets plastic pallets wooden pallets steel skids

7. Automation principle MH operations should be mechanized

and/or automated where feasible to improve operational efficiency, increase responsiveness, improve consistency and predictability, decrease operating costs.

ASRS is a perfect example.

8.Equipment selection principle Why? What? Where? When? How? Who? If we answer these questions about each

move, the solution will become evident.

9.The standardization principle standardize handling methods as well as

types and sizes of handling equipment too many sizes and brands of equipment

results in higher operational cost. A fewer sizes of carton will simplify the

storage.

10. The dead weight principle Try to reduce the ratio of equipment weight to product

weight. Don’t buy equipment that is bigger than necessary.

Reduce tare weight and save money.

11. The maintenance principle Plan for preventive maintenance and scheduled repairs

of all handling equipment. Pallets and storage facilities need repair too.

12. The capacity principle use handling equipment to help achieve desired

production capacity i.e. material handling equipment can help to maximize

production equipment utilization.

A punch press can cycle every 0.03 minute, but our time standard for manually loading and unloading this press is only 300 pieces per hour.

Press capacity = 60 min / 0.03 = 2000 pieces/hr

Utilization = 300 / 2000 = 15%

Should we buy a new press? If we can purchase a coil-feeding material handling

system, we could approach 100% press utilization.

Conveyors

Large Conveyors (2 axis)

Lifts

Chutes

AdvantagesDisadvantages1. More economical if large

volume of material moved to same place

2. One power supply to drive entire “belt” – more economical

3. Reduction in need for lot identification tags

4. Can be used to pace the workers

1. Less economical if material follows diverse paths

Cranes

Tracks - Monorail

Advantages Disadvantages

1. Can cover a wider area1. Still limited to area covered

Lift truckComputer Controlled Truck

Advantage Disadvantage

1. Flexible 1. Must have portable power supply with each piece of equipment

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Materials Handling, Storage, Use, and Disposal

Involves diverse operations:

Manual material handling Carrying bags or materials Unpacking materials

Material handling via machine Forklift Crane Rigging

Stacking or storing drums, barrels, kegs, lumber, loose bricks or other materials

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Injuries

Lifting objects is a major cause of back injuries in the work place

Improper storing and handling of material and equipment can cause struck by and crushed by injuries

Improper manual lifting or carrying loads that are too large or heavy

Being struck by materials or being caught in pinch points

Crushed by machines, falling materials or improperly stored materials

Incorrectly cutting ties or securing devices

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Seek help:• When a load is too bulky to properly grasp or lift • When you can’t see around or over the load• When you can’t safely handle the load

Attach handles to loads to reduce the chances of getting fingers smashed.

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Break load into partsGet help with heavy or bulky itemsLift with legs, keep back straight, do not twistUse handling aids - such as steps, trestles, shoulder pads, handles, and wheelsAvoid lifting above shoulder level

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What should be taught:• How to lift safely• How to avoid unnecessary

physical stress and strain• What you can comfortably

handle without undue strain

• Proper use of equipment• Recognizing potential

hazards and how to prevent / correct them

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For loads with sharp or rough edges, wear gloves or otherhand and forearm protection

When loads are heavy or bulky, wear steel-toed safety shoes toprevent foot injuries if the loadis dropped

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Employees must be trained in the proper use and limitations of the equipment they operate

This includes knowing how to effectively use equipment such as forklifts, cranes, and slings

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Center the load on the forks and as close to the mast as possible to minimize the potential for the truck tipping or load falling Overloading a lift truck makes it hard to control and could make it tip overPlace the load at the lowest position for travelingDon’t place extra weight on the rear of a counterbalanced forklift to allow an overload

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Keep arms and legs inside the truckHandle only stable loadsKeep speed low - you may have to stopBe careful when making sharp turnswith a raised loadIf a load blocks your view, travel in reverseNo riders, unless there’s an approved seatDon’t drive with forks raisedWear safety belts or other restraint devices

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• Truck-related topics• Workplace-related topics• Standard requirements• Trainees must be

supervised by a competent person and not endanger others

• Formal instruction• Practical training• Evaluation of

performance

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Dock boards must

have handholds, or

other effective means

for safe handling.

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Scrapers, loaders, crawler or wheel tractors, bulldozers, off-highway trucks, graders, tractors

Provide seat belts

Equipment with an obstructed rear view can’t be used in reverse unless the equipment has a signal alarm

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Check the load chart in the cab

Frequently inspect

Never lift people

Check overhead power lines

Ensure area of travel is clear

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Rigging Equipment Slings

Types of slings covered are those made from alloy steel chain, wire rope, metal mesh, natural or synthetic fiber rope, and synthetic web.

Chain Wire rope Metal mesh Synthetic

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Inspect slings:

Each day before use

Where service conditions warrant

Remove them from service ifdamaged or defective

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Remove From Service

Immediately remove damaged or defective slings from service

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Adapts to shape of the load

Can damage by sudden shocks

Best choice for hoisting very hot materials

Must have an affixed tag stating size, grade, rated capacity, and sling manufacturer

Alloy Steel Chains

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Markings Alloy Steel Chain

It must be marked with grade or manufacturer's mark

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Hooks, rings, oblong links, or other attachments, when used with alloy steel chains, must have a rated capacity at least equal to that of the chain

Alloy Steel Chain AttachmentsRated Capacity

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Job or shop hooks and links, or makeshift fasteners, formed from bolts, rods, etc., or other such attachments, can’t be used

Unsuitable Alloy Steel Chain Attachments

Right Wrong

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Chain Wear

When a chain shows excessive wear, or is cracked or pitted, remove it from service

Non-alloy repair links can not be used

Used to hoist materials

Selection considerations: strength ability to bend without cracking ability to withstand abrasive wear ability to withstand abuse

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Wire rope

Strand

Center

WireCore

Eye splices made in any wire rope must have at least three full tucks

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Cover or blunt protruding ends of strands

Protruding Ends

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Wire Rope Clips

When using U-bolt wire rope clips to form eyes, ensure the "U" section is in contact with the dead end of the rope

This is the correct method

Dead End

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Lubrication

Regularly lubricate ropes and chains

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Wire Rope Slings Remove From Service

If these happen, remove the wire rope sling from service

Crushing

KinkingBird Caging

Mark or code to show: Name or trademark

of manufacturer Rated capacities

for the type of hitch

Type of material

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Fittings must be: At least as strong

as that of the sling

Free of sharp edges that could damage the webbing

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Stitching is the only method allowed to attach end fittings to webbing, or to form eyes

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Stitching

Remove from service if any of these are present: Acid or caustic burns Melting or charring of

any part Snags, punctures, tears

or cuts Broken or worn stitches Distortion of fittings

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Heat Damage

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Storing Materials

Secure materials stored in tiers by stacking, racking, blocking, or interlocking to prevent them from falling

Post safe load limits of floors

Keep aisles and passageways clear

Don’t store noncompatible materials together

In buildings under construction, don’t place stored materials within 6 feet of a hoistway or floor opening

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Employees who work on stored materials in silos, hoppers, or tanks, must be equipped with lifelines and harnesses

Fall Protection

Stack bricks in a manner that will keep them from falling

Do not stack them more than 7 feet high

Taper back a loose brick stack after it is 4 feet high

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Remove nails before stacking

Stack on sills

Stack lumber so that it is stable and self supporting

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Housekeeping

Keep storage areas free from accumulated materials that cause tripping, fires, or explosions, or that may

contribute to harboring rats and pests

Use an enclosed chute when you drop material more than 20 feet outside of a building

If you drop debris through holes in the floor without chutes, enclose the drop area with barricades

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Remove all scrap lumber, waste material, and rubbish from the immediate work area as work progresses

Keep all solvent waste, oily rags, and flammable liquids in fire resistant covered containers until removed from worksite

Openings must be less than 25 percent of the whole floor

Floors weakened or made unsafe by demolition must be shored so they can safely carry the demolition load

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Manually handling materials When lifting objects, lift with your legs, keep your back

straight, do not twist, and use handling aids

Using cranes, forklifts, and slings to move materials

Watch for potential struck by and crushed by dangers For slings, check their load capacity, inspect them, and

remove them from service when they display signs of stress or wear

Also - Keep work areas free from debris and materials Store materials safely to avoid struck by/crushed by

hazards

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