Mechanization of Parts Handling

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

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

Motion & Transfer Start Parts Moving Natural methods used: > Gravity > Centrifugal Force > Tumbling > Air Pressure > Vibration

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

Vibratory Bowls Small Parts Commercially Available Recycling Principle > Parts that don’t line up; start over. Wide Variety of Part Shapes Random Orientation Recognize Geometry > Irregularities designed to push, release incorrect orientations. Travel Uphill > Ledges & Tracks: Spiral around & up.

Principles of Parts Orientation Active: Orient by Rearrangement Passive: Orient by Rejection

Vibratory Bowl Analysis Feed Efficiency Effect of the Stations Efficiency of the System Recycled Parts Effect of the Step Device Optimization of Step Height

Measure Of Feed Efficiency Efficiency = OUTPUT INPUT Output is the number of correctly orientated parts delivered by the system. Input is the number of parts entering the system.

Family of Parts ( Same Basic Shape) Plain Cylinders with Blind Hole Drilled Axially from One End

Variable Length to Diameter Ratio l/d = length / diameter

Possible Part Alignments Four: a (Desired) b 1 b 2 c

Natural Resting Aspects Describes the way a part can rest on a Horizontal Surface

Input Matrix for Part 7 (l/d = 1.132) [a b 1 b 2 c] = ( )

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

Impact Of Step Device 50 % parts enter as a exit as a 100% parts enter as b 1 exit as a 30% parts enter as b 2 exit as a 80% parts enter as c exit as a

Efficiency of the System Input x Impact = Efficiency of Alignment a.27 x.50 =.135 b 1.35 x 1.00 =.350 b 2.35 x.30 =.105 c.03 x.80 =.024 Total.614 Efficiency of the System = 61.4%

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

Probability the part will be kicked back k times P k = [ E/100 ] [ 1 – E/100 ] k Where: E = Efficiency of the system k = Number of kickbacks

System Recycled Parts P 0 = (.614)(.386) 0 = P 1 = (.614)(.386) 1 = P 2 = (.614)(.386) 2 = P 3 = (.614)(.386) 3 = P 10 = (.614)(.386) 10 = Five out of a Hundred Thousand will be kicked back (10) times before achieving an acceptable alignment.

Average Number of Kickbacks k AVE = 1 – E/100 E/100 This Example: k AVE = / =

Optimization of Step Height Calculate the System Efficiently for increments of step height within practical range. Maximum Allowable = 7 mm Goal: Optimize design for each of the 8 parts. Find the step height that gives the maximum efficiency.

Summary Graph of Part Shape Effect on Efficiency of Orienting System > No Step Device > One Step Device > Two Step Devices