AZ Automotive Weld Tooling & Assembly Equipment Standards Revision 1.4 23Sep2004
PRINTED COPIES ARE UNCONTROLLED
Deviations that improve safety, quality, or cost ARE ALWAYS WELCOME.
SECTION 15
This document attempts to integrate new technology around the human infrastructure by establishing uniform ergonomic guidelines for AZ Automotive’s manufacturing and assembly operations, as well as part distribution centers. These guidelines should be used as distinct specifications for designers, builders, suppliers, contractors etc. providing new materials, services, tools, processes, facilities, task designs, and product components to AZ Automotive. This document is to be used as a trigger point in determining if an ergonomic assessment of a particular workstation is required.
Designers, builders, suppliers, contractors etc. (which will be referred to as Supplier) providing new materials, services, tools, processes, facilities, task designs, and product components to AZ Automotive must undertake to electronically invite the appropriate AZ Automotive Design for Manufacturing representative (refer to Table 1 below) to review and approve the design plans at the simultaneous engineering phase and at the 40% design review. A minimum of 10 days of lead time notification should be provided to AZ Automotive when setting these buy off meetings. Appropriate directions and contact information must also be provided in the meeting invitation. Prior to the meeting the supplier shall undertake to fully fill out the AZ Automotive Ergonomics Buy off form found in Section 15.6.2 of this Tool Design Standard as required by the procedure described in Section 15.6.1 of this document.
15.1.1.1
For production tasks the maximum cyclic two handed lift is 9 kg (20 lbs.). New requisitions for lift assists require prior approval from an AZ Automotive DFM Manager (refer to Table 1).
15.1.1.2
The maximum cyclic two handed push/pull force is 196 N (44 lbs.) initial and 107 N (24 lbs.) sustained. The force measurement must reflect appropriate acceleration rates that would be used by the manufacturing plant based on their cycle time.
15.1.1.3
For production tasks the maximum cyclic two handed carry is 14 kg (30 lbs.).
15.1.1.4
The maximum small lot container weight (including material and container) is 14 kg (30 lbs.).
15.1.1.5
Maximum lateral force applied horizontally at full arm's extension in front of a body is 67 N (15 lbs.).
15.1.2. Material Handling Methods and Task Geometry
15.1.2.1
For production tasks the maximum cyclic horizontal carry distance is 6 m (20 ft.).
15.1.2.2
Minimize the horizontal distance of any push, pull or carry.
15.1.2.3
Maximum horizontal reach measured from the edge of any barrier (tool, fixture, vehicle, etc.) between the worker and the task when lifting is 51 cm (20"). This specification assumes compliance with 15.3.5.4 and 15.3.1.12.
15.1.2.4
Minimize the horizontal reach distance at the origin and the destination of lift or lower.
15.1.2.5
Minimize the vertical travel distance of the hands between the destination and the origin of lift or lower.
15.1.2.6
Minimize the frequency of lifts or lowers.
15.1.2.7
Minimize overhead weight manually supported and its duration.
15.1.2.8
Minimize the need to push or pull. (Use conveyors, power trucks, lift tables, turn tables, or gravity slides/chutes whenever possible).
15.1.2.9
Use gravity to move material.
15.1.2.10
Convert lift/lower combined with a carry to a push or pull using facilities including powered and non-powered conveyors, ball roller tables and handcarts.
15.1.2.11
Replace carry with a push or pull using facilities including conveyors (all kinds), tables and slides between work stations, carts, and lift trucks where applicable.
15.1.2.12
Replace a pull with a push whenever possible.
15.1.3. Dunnage/Material Racks
15.1.3.1
Design material packaging such that the parts are easy to grasp and manipulate with one hand using no grasping tools. Material packaging design should allow the operator to grasp parts with either a power grip or a hook grasp as opposed to a pinch grip.
15.1.3.2
The operator should not be assigned to step up or down incoming material racks to obtain material. Appropriate material display platforms must be provided.
15.1.3.3
Material handling racks must have lightweight returnable dunnage and/or counter weighted dunnage bars, each weighing a maximum of 14 kg (30 lbs.). The material must be oriented in assembly position. Material rack designs must also facilitate the use of lift assists for material unloading as required.
15.1.3.4
Returnable dunnage should have interchangeable cap and base.
15.1.3.5
Dunnage layer separators that require rotation for high-density stacking returns are not recommended.
15.1.3.6
Provide a pick up point on the dunnage layers, located at its center of gravity, with similar geometry to those found on parts. This dunnage pick up point will provide the opportunity of using the part load hoist to move and aside the empty dunnage layers.
15.1.4. Material Handling Devices
15.1.4.1
Minimize the manual handling of materials. Use initiatives including lift tables, articulating arms, lift trucks, hoists, conveyors, gravity dumps or chutes, palletized material and bulk handling.
15.1.4.2
Ensure that articulating arm and lift device designs include consideration of the product, dunnage, production rate, shop floor layout, Ergonomic Guidelines, Tooling Do’s and Don’t’s, MTI and SMI Safety Standards, and test trials of actual plant conditions.
15.1.4.3
Maximize all pushcart caster diameters. Provide push handles between 91.5 - 112 cm (36 to 44") above the floor. Consider using 25.5 cm (10") diameter very low starting and rolling resistance casters.
15.1.5. Handles
15.1.5.1
One-handed cut out handles shall have a minimum of 13 cm (5") in width with a 6 cm (2.5") hand clearance.
15.1.5.2
Two-handed cut out handles shall have a minimum of 25.5 cm (10") in width with a 6 cm (2.5") hand clearance.
15.1.5.3
The maximum handle diameter for full encirclement by the hand is 38 mm (1.5").
15.1.5.4
The minimum handle diameter for comfort is 6.5 mm (0.25") for loads up to 7 kg (15 lbs.); 13 mm (0.5") for loads between 7 - 9 kg (15-20 lbs).; and 19 mm (0.75") for loads over 9 kg (20 lbs.). Make handle diameters as close as possible to 38 mm (1.5").
15.1.5.5
Handles should be located at or above the line passing through the center of gravity of the load.
15.1.5.6
Loads weighing more than 4.5 kg (10 lbs.) must have good hand coupling. Refer to 15.2.2.4 for proper handle designs style and dimensions that enhance coupling.
15.1.5.7
Manually lifted bulky or unstable loads weighing more than 18 kg (40 lbs.) must have a good hand coupling for multiple person lifting.
15.1.5.8
Handles shall have surface material that has a high coefficient of friction to reduce slippage and the required grip force.
15.2.1.1
The maximum pinch force is 9 N (2 lbs.).
15.2.1.2
Maximum push button force is 13 N (3 lbs.). When these forces are applied to hoist pendant controls, functional grip span must not exceed 9.5 cm (3.7").
15.2.1.3
Eliminate palm buttons where possible. When necessary, select REES low force 8.5 N (1.9 lb.) palm buttons # 04957-012, for palm buttons cycle initiation applications. The spacing between the palm button should not exceed 61 cm (24"). Static force application to palm buttons must not exceed 4 seconds in duration per cycle.
15.2.1.4
Maximum hand crank control forces are 22 N (5 lbs.).
15.2.1.5
Eliminate hand tool feed force. (Consider using weld nuts and the use of hex or torx head rather than slotted or Phillips head screws.)
15.2.1.6
Make levers as long as practical to maximize mechanical advantage. The maximum manual lever force requirement is 129 N (29 lbs.).
15.2.2. Tool Handle and Activation
15.2.2.1
The sealer or paint gun trigger grip force is 5 - 25 N (1 - 6 lbs.). Two finger activation triggers are preferred over one finger triggers. Thumb trigger activation devices are not recommended for repetitive operations. Articulating surfaces such as cycle buttons, levers or triggers shall be designed to minimize contact stress on the skin surfaces while providing positive off -- on differentiation sensory feedback.
15.2.2.2
Maximum grip strength is achieved with a hand tool grip span between 7.5 - 8 cm (2.9" to 3.1"). The maximum grip force is 45 N (10 lbs.).
15.2.2.3
Manual hand tooling with hinged design such as pliers must be equipped with appropriate spring loaded return assist mechanisms, when assigned to be used on a frequent cyclic basis.
15.2.2.4
Make the tool handle diameters as close as possible to 4 cm (1.5") with a minimum of 11.5 cm (4.5") in length. Surface materials must have a high coefficient of friction to minimize the required grip force. The holding and controlling surface of the tools should be designed without deep grooves, sharp edges or fluted finger surfaces. For a tool used with a power grip, the tool must be designed, whenever possible, with an oval shaped handle 3 cm by 4.5 cm (1.25" by 1.75") in diameter. If an oval shaped handle cannot be used, select a circular handle of at least 4 cm (1.5") in diameter. Tool handles should be equipped with a flange to prevent the tool from slipping out of the hand. Tools in which an axial force is applied such as punches should be equipped with a 15 mm (0.6") flanges to prevent the hand from slipping off the handle and to guard the hand from hammer contact and collision with a rigid surface.
15.2.2.5
Tool handles must extend beyond the palm of the hand with a minimum length of 11.5 cm (4.5").
15.2.2.6
Provide padded and rounded surfaces on hand tools and fixtures.
15.2.2.7
Use four-finger throttle on right-angled, crow foot and tube nut runner power tools. Locate the power tool throttle opposite the torque reaction force for non-reversing tools or opposite the work task on reversing tools. For example if a reversing tool is used overhead the throttle should be facing downward. Consult your corporate power tool specialist for further assistance.
15.2.3. Tool Selection
15.2.3.1
Use only AZ Automotive Corporate approved power tools.
15.2.3.2
Minimize the weight of manually handled hand / power tools and fixtures. Ensure that all tools are appropriately balanced and in the "in-use" position, to avoid additional manipulation of the tool.
15.2.3.3
Select hand tools with minimal vibration. Power tool vibration levels must not exceed 4 m/s2 using the testing protocol defined in ISO 5349.2. Ensure that all power tool attachments such as sanding disks, extension, sockets etc. are balanced and mechanically secure to minimize the avoidable vibration.
15.2.3.4
Pulse tools are preferred. Mandatory tools should be lightweight, low force, fitted to the hand and designed for one-handed use.
15.2.3.5
Provide air line swivel couplings between at the power tool / hose interface, particularly where more than one position or posture per cycle will be used.
15.2.3.6
Pneumatic air tool exhausts must be adjusted to direct exhaust air away from the worker.
15.2.3.7
Equipment must be designed so that convenient accessibility is provided for maintenance facilities and tools must be designed such that maintenance related service controls, instruments, lube points, shut off valves etc. are visible and fully accessible from the shop floor in a convenient location outside of machine guarding.
15.2.4. Reaction Torque Control
15.2.4.1
Pneumatic nut runners shall be equipped with an automatic shut-off to achieve a pre-set torque with greater precision while minimizing the torque reaction stress on the operator.
15.2.4.2
Right angled, tube nut runner and crowfoot hand held continuous drive power tools with shut off mechanisms exceeding 50 Nm (37 ft. lbs.) must use a reaction bar or articulating arm.
15.2.4.3
Pistol grip continuous drive power hand tools with shut off mechanisms exceeding 30 Nm (26 ft. lbs.) must use an aluminum reaction bar.
15.2.4.4
In line continuous drive hand held power tools exceeding 16 Nm (14 ft. lbs.) must use an aluminum reaction bar or articulating arm
15.2.5. Tool Support
15.2.5.1
Use a lift assist to support the weight of tools or fixtures when they weigh > 3 kg (7 lbs.) and are used frequently; or weigh > 11 kg (25 lbs.) and are used infrequently. The tool support attachment location should be located at the tool's center of gravity when all connection devices are attached.
15.2.6. Controls and Displays
15.2.6.1
Minimize the total number of operator controls. The location of the controls and indicators shall take into account their importance, frequency and sequence of use. The arrangement of controls should be compatible with their associated displays or machine functions. Controls should be located close to the associated display and arranged in a logical manner with respect to displays. Controls should be positioned to allow equipment and machinery operations with the upper limb joints in neutral position between 91.5 - 123 cm (36" and 48") above the worker supporting surface. Controls spacing and clearances should be adequate for an operator wearing gloves or other necessary protective equipment. Sensitivity gain relationships of controls should be appropriate for the task as described below:
|
Up (Right) |
Down (Left) |
Up (Right) |
Down (Left) |
|
on |
Off |
up |
down |
|
high |
Low |
faster |
slower |
|
open |
Close |
increase |
decrease |
|
in |
Out |
start |
stop |
|
raise |
Lower |
accelerate |
decelerate |
15.2.6.2
Locate controls/indicators according to their importance, frequency and sequence of use. Use digital display when precise values are needed. Analog displays, such as dials should be used to monitor rate of changes and for comparison within defined limits. Analog dial pointers should be aligned to indicate normal functioning. Color coded dials should be provided to indicate operating conditions. Appropriate character sizes on the dials should be provided for effective inspection.
Optimal indicator character height (mm) = horizontal distance (mm) / 200
Minimize the need for workers to be inside of the vehicle during assembly. Articulated arm seated personnel carriers should be considered as an alternative for inside of vehicle assembly tasks.
15.3.1.1
Design a job with a variety of muscles and postures used in every cycle.
15.3.1.2
Design a job such that both hands can be used.
15.3.1.3
Whole body vibration levels must be minimized. Critical whole body resonance frequencies are between 2-200 Hz.
15.3.1.4
Minimize the need for workers to be inside of the vehicle during assembly. Articulated arm seated personnel carriers should be considered as an alternative for inside of vehicle assembly tasks.
15.3.1.5
Minimize twisting and deviated work postures in the task design (work in front of the body).
15.3.1.6
Minimize the need for operators to walk backwards with extended reaches. Utilize skillets with lifts, moving sidewalks, synchronous carriers or reverse the direction of flow of the vehicle during assembly to avoid these conditions.
15.3.1.7
The maximum two handed cyclic vertical downward pull force is 107 N (24 lbs.).
15.3.1.8
Ensure the worker's hands are in line with their forearms (i.e. keep wrists straight).
15.3.1.9
Keep the worker's palms facing each other (not facing up or down).
15.3.1.10
Keep the worker's upper arms hanging near vertical to the sides of the body.
15.3.1.11
Consider automating or Purchased in Assembly (P.I.A.) of highly repetitive tasks.
15.3.1.12
Based on the preponderance of studies seated work is not usually an acceptable approach for manufacturing operations. Approved seated workstations must be provided with a horizontal leg clearance of 66 cm (26") and a work surface height of 76 cm (30") above the supporting surface and an AZ Automotive Corporate approved chair. Articulating arm personnel carriers offering seated postures for vehicle interior assembly are acceptable and can be a preferred process alternative on specific assembly tasks to the awkward postures often assumed by the workers assigned to perform assembly tasks on the interior of the vehicles.
15.3.2. Workstation Layout
15.3.2.1
Keep tools and work in front of the worker
15.3.2.2
Eliminate reaching behind the worker.
15.3.2.3
Place more frequently used objects closer to the worker.
15.3.2.4
Place heavier objects closer to the worker.
15.3.2.5
The operator should not be assigned to step up or down between workstation elevations during the normal work cycle. Appropriate level workstation platforms must be provided.
15.3.2.6
Video display tube heights should be adjustable with the center between 122 - 152 cm (48" - 60") above worker support surface for standing workstations.
15.3.3. Working Height
15.3.3.1
For standing workstations the optimal task height (location of hands when working) is 104 cm (41") above the worker support surface.
15.3.3.2
The recommended work envelope (location of hands when working) is between 91 - 122 cm (36" - 48") above the standing support surface.
15.3.3.3
Provide fixtures or a surface area to support objects being worked on.
15.3.3.4
If the workstation cannot be lowered, consider the use of platforms.
15.3.4. Reach Distance
15.3.4.1
Reach envelopes should consider the smallest users (i.e. 5th percentile females). The anthropometry data referenced should be an appropriate approximation of the working population that will be using the workstation.
15.3.4.2
Minimize horizontal reach distances to perform manual task. The maximum horizontal reach distance is 51 cm (20"). Tooling and conveyor infrastructures such as air lines, electrical conduits, machine guarding, structural supports and emergency stop cables shall not be located between the worker and the manual tasks in such a way that the reaches are increased by their physical presence.
15.3.4.3
Place frequently used tools and parts within 38 cm (15") of the worker and minimize horizontal non-lifting reaches > 51 cm (20").
15.3.5. Clearances
15.3.5.1
Clearance allowances should consider the largest users (e.g. 95th percentile males). The anthropometry data referenced should be an appropriate approximation of the working population that will be using the workstation.
15.3.5.2
Use a minimum clearance of 46 cm (18") between moving objects and fixed structures.
15.3.5.3
Use a minimum of 203 cm (80") above the floor for overhead clearance for standing workstations.
15.3.5.4
Provide standing workstation foot clearance along the length of that workstation with 15 cm (6") depth and 10 cm (4") height clearance.
15.3.5.5
The minimum width for clearance in areas where workers are required to walk is 71 cm (28").
15.3.5.6
Provide an unobstructed workspace having a three dimensional cylindrical shape with a minimum of 122 cm (48") in diameter when manual material handling is required.
15.3.5.7
The minimum dynamic workspace per person has a three dimensional cylindrical shape with a diameter of 69 cm (27").
15.3.6. Auditory Signals
15.3.6.1
Use auditory signals when a quick response is critical.
15.3.6.2
Auditory signals must be at least 15 dBa above background environmental sound levels.
15.3.6.3
Please refer to the OSHA Sound Level Specification for Industrial Machinery and Equipment for noise control design guidelines.
15.3.7. Visual Considerations
15.3.7.1
Consider vision systems for repetitive complex inspection tasks.
15.3.7.2
Provide artificial lights with minimum shadows and glare if required.
15.3.7.3
The normal viewing distance is 46 cm (18") with a minimum of 33 cm (13") and a maximum of 71 cm (28").
15.3.7.4
Design the task with a minimal blind or hidden assembly requirements.
Select the GENICOM Safework human model and the Deneb digital manufacturing simulation software. The digital design criteria must accommodate 95% of the manufacturing population at the specific geographical region where task designs are being prepared.
Maximum acceptable time weighted average metabolic energy consumption is 4.5 Kcal/minute.
Manual material handling tasks must be acceptable to 75% of the female population using the published paper authored by Stover Snook and Vincent Ciriello (Ergonomics, 1991, Vol. 34, No. 9, 1197-1213).
AZ Automotive will undertake to conduct digital assembly mock up simulations as required.
Supplier Roles and Responsibilities
Designers, builders, suppliers, contractors, etc. (which will be referred to as Supplier) who provide new and refurbished materials, services, tools, processes, facilities, task designs, and product components to AZ Automotive shall:
•make all reasonable efforts to implement all of the recommendations and requirements of Section 15 of the AZ Automotive Tool Design Standards Do's and Don'ts,
•integrate Section 15 into their decision making process as early as possible in the engineering design phases.
•make every effort to implement the most effective low cost engineering controls and solutions when accommodating the requirements of Section 15,
•undertake to obtain professional ergonomic guidance and direction from a competent Certified Professional Ergonomist (CPE) or equivalent as required to evaluate and assess compromised requirements. The supplier shall provide copies of these ergonomic assessments to the AZ Automotive DFM Manager at the buy off meeting, and
•undertake to electronically invite the appropriate AZ Automotive Design for Manufacturing Manager as illustrated in Table via e-mail to review and approve the design plans at the engineering concept phase and at the 40% process design review. A minimum of 10 days of lead-time notification should be provided to AZ Automotive when setting up these buy off meetings. Appropriate local directions and contract information must also be provided in the electronic meeting invitation.