Allowances Practice Problems

Example 1 Suppose you have a fine assembly task –Standing –Requires approximately 300 kCal / hr (based on HR measurement) –NT = 90 cmin. –Additional Considerations include Illumination – 25 fc in work area Noise – fairly continuous 91 dBA in work area Heat – First hot day of the year, WBGT = 80 °F No significant mental strain, monotony, or repetitiveness. What is the Standard Time?

Example 1 (cont’d) ST = NT (1+ allowances) 2 ways to find allowances –Quick & Dirty way Table 11-2 (ILO Recommendations) –More thorough way Calculate individual relaxation allowances, RA, for each variable and special allowance factor.

ILO Recommendations Table 11-2, Niebel & Frievalds p. 437

Example 1 (cont’d) More thorough method –Use Table 11-11, p Some factors can be found directly from the table –Constant –Posture –Visual Strain Others must be calculated.

Example 1 (cont’d) Personal needs = 5% (always constant) Basic Fatigue = 4% (always constant Posture – standing = 2% –Why isn’t there an option for seated? Visual Strain – Fine assembly = 2% Mental Stress, Monotony, Repetitiveness = 0%.

Example 1 (cont’d) Illumination –Looks like a chart lookup, but what are IES subcategories? Refer to Ch. 6, p. 237, Table 6-2. Our illumination = 25 fc, or CAT D. What should our illumination category be? –Do you see “fine assembly” listed? –Should be between “medium” & “extra-fine” assembly. –Should be CAT F, but we are 2 categories below. From Table 11-11, illumination allowance = 3%

Example 1 (cont’d) Atmospheric Conditions (HEAT) –Workload, W = 300 kcal/hr –WBGT = 80 °F How do you determine WBGT? –RA = e ( W WBGT) – = e ( x x80) – = e (3.09) = 22% –Can also lookup RAL from Fig 6-11, p RAL for 300 kcal/hr & WBGT = 80 °F is 48 min/hr –12 min rest / 48 min work = 25% allowance.

Example 1 – (cont’d) Noise –SPL = 91 dBA What is SPL –Need to calculate dose for 8 hour day. If 90 dBA is 8 hour-100% dose, what about 91dBA? Must find time for 100% dose T = 8 / 2 [(L-90)/5] T = 8 / 2 [(91-90)/5]. T = 6.96 hours is a 100% dose for 91 dBA. D = 8/6.96 = –RA = 100 x (D – 1) – = 100 x (1.15-1) –RA = 15%

Example 1 (cont’d) Find Standard Time –ST = NT x (1 + Σ allowances) –ST = 90 cmin x ( ) –ST = 90 cmin x ( ) » HEAT NOISE –ST = 90 x (1.53) –ST = cmin

Example 1 - Redesign As a process engineer, what would be the first things you would want to do to bring the standard time closer to the NT? –The heat allowance is the largest? It can be reduced to eliminate extra heat fatigue. How? –The noise allowance is the next largest What would you do about that one?

Measurement How do you measure… –Illumination? –Heat? –Noise? For the next 3 labs, you will practice measuring these three environmental factors –This week, we will begin with noise. You will write one report that considers the impact of these three factors on work performance –based on the data you will collect –AND, based on some homework problems you will receive in lab.

Homework Work the following problems –Ch. 11 – Prob #1, 2, 3, 5 & 7. Due one week from today. This is in addition to the homework you will receive in lab today!! –But, there’s no report due next week.