Mechanization of Mechanization of Parts HandlingParts Handling

Parts FeedingParts Feeding

Fabricated parts must be Fabricated parts must be transported, selected, transported, selected, oriented properly, and oriented properly, and positioned for assembly.positioned for assembly.

Parts Source CompatibilityParts Source Compatibility

When writing specifications for When writing specifications for purchased parts & when purchased parts & when qualifying vendors, the qualifying vendors, the packaging & orientation of parts packaging & orientation of parts should be a consideration.should be a consideration.

Motion & TransferMotion & Transfer

Start Parts MovingStart Parts MovingNatural methods used:Natural methods used:

> Gravity> Gravity> Centrifugal Force> Centrifugal Force> Tumbling> Tumbling> Air Pressure> Air Pressure> Vibration> Vibration

Parts Handling SystemParts Handling System

Desired Features:Desired Features:> No damage to parts> No damage to parts> Reliable operation> Reliable operation> Accurately locate parts> Accurately locate parts> Sufficient transfer speed> Sufficient transfer speed> Minimum direct labor> Minimum direct labor> Large carrying capacity> Large carrying capacity

Vibratory BowlsVibratory BowlsSmall PartsSmall PartsCommercially AvailableCommercially AvailableRecycling PrincipleRecycling Principle

> Parts that don’t line up; start over.> Parts that don’t line up; start over.

Wide Variety of Part ShapesWide Variety of Part ShapesRandom OrientationRandom OrientationRecognize GeometryRecognize Geometry

> Irregularities designed to push, release> Irregularities designed to push, release incorrect orientations. incorrect orientations.

Travel Uphill Travel Uphill > Ledges & Tracks: Spiral around & up. > Ledges & Tracks: Spiral around & up.

Principles of Parts OrientationPrinciples of Parts Orientation

Active: Active: Orient by RearrangementOrient by Rearrangement

Passive:Passive:Orient by RejectionOrient by Rejection

Vibratory Bowl AnalysisVibratory Bowl Analysis

Feed EfficiencyFeed EfficiencyEffect of the StationsEffect of the StationsEfficiency of the SystemEfficiency of the SystemRecycled PartsRecycled PartsEffect of the Step Device Effect of the Step Device Optimization of Step HeightOptimization of Step Height

Measure Of Feed EfficiencyMeasure Of Feed Efficiency

Efficiency = Efficiency = OUTPUT OUTPUT

INPUT INPUT

Output is the number of correctly orientated Output is the number of correctly orientated parts delivered by the system.parts delivered by the system.Input is the number of parts entering the Input is the number of parts entering the

system.system.

Family of PartsFamily of Parts((Same Basic Shape)Same Basic Shape)

Plain Cylinders with Blind Plain Cylinders with Blind Hole Drilled Axially from Hole Drilled Axially from One EndOne End

VariableVariable

Length to Diameter Length to Diameter RatioRatio

l/d = length / diameterl/d = length / diameter

Possible Part AlignmentsPossible Part Alignments

Four:Four:a a (Desired) (Desired)

bb11

bb22

cc

Natural Resting AspectsNatural Resting Aspects

Describes the way a part can Describes the way a part can rest on a Horizontal Surfacerest on a Horizontal Surface

Input MatrixInput Matrix

for Part 7 (l/d = 1.132)for Part 7 (l/d = 1.132)

[[a ba b11 b b22 c c] = (.27 .35 .35 .03)] = (.27 .35 .35 .03)

Effect of Step DeviceEffect of Step Device

Purpose is to increase Purpose is to increase the proportion of parts in the proportion of parts in alignment “alignment “a”a”..

Impact Of Step DeviceImpact Of Step Device

50 % parts enter as 50 % parts enter as aa exit as exit as aa100% parts enter as 100% parts enter as bb11 exit as exit as aa

30% parts enter as 30% parts enter as bb22 exit as exit as aa

80% parts enter as80% parts enter as c c exit as exit as aa

Efficiency of the SystemEfficiency of the System

Input x Impact = Efficiency of Input x Impact = Efficiency of Alignment Alignment

aa .27 x .50 = .135.27 x .50 = .135bb11 .35 x 1.00 = .350.35 x 1.00 = .350

bb22 .35 x .30 .35 x .30 = .105 = .105

cc .03.03 x .80 = .024 x .80 = .024 Total Total .614 .614

Efficiency of the System = 61.4%Efficiency of the System = 61.4%

Recycled PartsRecycled Parts

Calculate the chances Calculate the chances (probability) that a part will be (probability) that a part will be tossed back tossed back kk times before times before reaching an acceptable reaching an acceptable alignment.alignment.

Probability the part will be Probability the part will be kicked back k timeskicked back k times

PPk k = [ E/100 ] [ 1 – E/100 ]= [ E/100 ] [ 1 – E/100 ]kk

Where:Where:E = Efficiency of the systemE = Efficiency of the systemk = Number of kickbacksk = Number of kickbacks

System Recycled PartsSystem Recycled Parts

PP0 0 = (.614)(.386) = (.614)(.386)00 = 0.614 = 0.614

PP1 1 = (.614)(.386) = (.614)(.386)11 = 0.237 = 0.237

PP22 = (.614)(.386) = (.614)(.386)22 = 0.0915 = 0.0915

PP33 = (.614)(.386) = (.614)(.386)33 = 0.0353 = 0.0353

PP1010 = (.614)(.386) = (.614)(.386)1010 = 0.00005 = 0.00005Five out of a Hundred Thousand will be Five out of a Hundred Thousand will be kicked back (10) times before achieving kicked back (10) times before achieving an acceptable alignment.an acceptable alignment.

Average Number of KickbacksAverage Number of Kickbacks

kkAVEAVE = = 1 – E/1001 – E/100

E/100E/100

This Example:This Example:kkAVEAVE = 0.386 / 0.614 = 0.6287 = 0.386 / 0.614 = 0.6287

Optimization of Step HeightOptimization of Step Height

Calculate the System Efficiently Calculate the System Efficiently for increments of step height for increments of step height within practical range.within practical range.

Maximum Allowable = 7 mmMaximum Allowable = 7 mmGoal:Goal:Optimize design for each of the 8 parts. Find Optimize design for each of the 8 parts. Find the step height that gives the maximum the step height that gives the maximum efficiency.efficiency.

Summary Graph of Part Summary Graph of Part Shape Effect on Shape Effect on Efficiency of Orienting Efficiency of Orienting SystemSystem

> No Step Device> No Step Device> One Step Device> One Step Device> Two Step Devices> Two Step Devices