Glovebox gloves form the physical interface between the operator and the work inside the enclosure. Their size, shape, material and fit can influence hand posture, grip, tactile feedback, dexterity, fatigue and the time required to perform a task.
Good glovebox ergonomic design therefore involves more than providing an opening large enough for the hand. The glove should be considered as part of the complete human-machine interface together with the gloveport, task, tools, operator population and required working reach.
A glovebox glove must allow the operator to reach, grip and manipulate objects while maintaining the required enclosure boundary. Unlike an ordinary protective glove worn directly on the hand, the glovebox glove is attached to the enclosure and must accommodate a range of operators.
Poor anatomical fit can alter the way the fingers, thumb, wrist and forearm move during a task. Excess glove length, insufficient finger length, incorrect thumb position or unsuitable wrist-to-finger-web dimensions can all affect manipulation.
Publicly released LANL research reported that an earlier glove design, dating from the 1960s, was not based on true hand anatomy. Identified issues included short fingers, inappropriate wrist-to-finger-web length, absence of joint angles and incorrect thumb placement.
Source: Lawton, C. M., Develop and Manufacture an Ergonomically Sound Glovebox Glove Report, Los Alamos National Laboratory, LA-UR-17-29530, 2017, DOE OSTI 1402566.
Designing a glove around an average hand is unlikely to provide an equally good interface for the complete workforce.
LANL's improved glovebox-glove design considered workers ranging from the 5th-percentile female to the 95th-percentile male. Anthropometric hand measurements were combined with measurements from glovebox workers to establish the design.
The resulting glove incorporated more than forty dimensions. LANL also reports collaboration with orthopaedic hand surgeons during the development of the design.
Source: Lawton, C. M., LA-UR-17-29530, 2017.
Hand length and breadth alone do not completely define glove fit. The relationship between the fingers, thumb, finger web spaces, joints and wrist influences the movement available to the operator.
Important glove-design dimensions can therefore include:
The importance of these relationships is demonstrated by the LANL redesign, which moved from a relatively simple historical glove form to a three-dimensional model based on detailed hand anatomy.
Source: Lawton, C. M., LA-UR-17-29530, 2017.
The hand adopts different configurations depending on the object and task. Fine manipulation may rely heavily on the fingers and thumb, while larger objects can require a whole-hand or power grip.
Glove geometry should therefore allow useful movement of the thumb and fingers without forcing the hand into an unnecessarily strained position. A glove that is acceptable for holding a large object may perform quite differently during precision manipulation of a small component or tool.
The effect of the glove should be considered together with object size, shape, surface, required force and the duration and repetition of the task.
See: Hand Grasping and Grip Size .
Dexterity is particularly important where glovebox work involves tools, small components, fasteners, controls or other operations requiring accurate hand positioning.
Glovebox gloves can reduce dexterity compared with unrestricted bare-hand operation. The degree of interference depends on factors including glove fit, geometry, material construction and the task being performed.
LANL has published research comparing glovebox glove designs and materials using task-performance and dexterity testing. This work demonstrates that glove selection is not solely a containment or material-selection issue; the effect on operator task performance is also an engineering consideration.
Source: Castro, A. M., Lawton, C. M., Cournoyer, M. E. and Blask, C. L., Glovebox Glove Dexterity Comparison, Journal of Chemical Health & Safety, Vol. 19, No. 2, 2012, pp. 3–10, DOI 10.1016/j.jchas.2011.05.010.
The improved LANL glove design was tested against the glove design then in use. The evaluation included a subjective survey together with four dexterity tests.
LANL reported that the prototype produced statistically significant results in three of the four dexterity tests and favourable results on eight of ten survey questions.
This is useful from an engineering-design perspective because it demonstrates the value of testing an ergonomic intervention using actual task-performance measures rather than relying solely on dimensional comparison or subjective preference.
Source: Lawton, C. M., Develop and Manufacture an Ergonomically Sound Glovebox Glove Report, LA-UR-17-29530, 2017.
Glove material and construction can influence the resistance experienced by the hand and the dexterity available to the operator. Increasing protection or changing material properties can therefore have human-factors consequences as well as containment and durability consequences.
A published LANL study compared several glovebox-glove constructions with respect to dexterity and task performance. The work included glove formulations of different materials and thicknesses and assessed their effect on operator performance.
Source: Castro, A. M. et al., Glovebox Glove Dexterity Comparison, Journal of Chemical Health & Safety, 19(2), 2012, 3–10.
Glovebox operations may involve repeated gripping, manipulation or tool use. The ergonomic significance of a glove therefore depends not only on whether an operator can perform a particular movement once, but also on the physical demand created when the movement is repeated for an extended period.
LANL researchers have specifically identified extended-duration and high-repetition hand tasks as important considerations in glovebox work. Their published work notes that poorly fitting gloves can increase discomfort and injury risk, increase the time required to perform work and place additional stress on the glove itself.
Source: Chan, M., Lawton, C. and Ticknor, L., Dexterity and Worker Comfort in an Ergonomically Designed Glovebox Glove, Transactions of the American Nuclear Society, Vol. 116, 2017, pp. 765–766.
Tools introduce another interface between the glove and the task. Handle diameter, shape, orientation, required operating force and the precision of the operation can all influence hand and wrist posture.
A tool suitable for unrestricted use may not necessarily provide the same level of control when operated through a glovebox glove. Where tools are used frequently, their handles and operating forces should be considered together with glove characteristics and the available working posture.
Frequently used tools should also be positioned within a favourable working reach where practicable.
See: Machine Interfaces and Controls and Glovebox Reach and Gloveport Position .
An ergonomic problem does not necessarily appear as an immediate inability to perform the task. Poor fit or reduced dexterity may instead increase the time required to complete an operation.
This matters because additional task time can also increase the duration of an awkward posture, the number of corrective hand movements and the period for which muscular effort must be sustained.
Task completion time can therefore be a useful measure when comparing glove designs or evaluating proposed changes, provided that learning effects and differences between operators are properly considered.
When assessing glovebox gloves from a human-factors perspective, engineers should consider:
A glovebox glove should be treated as an engineered human-machine interface, not simply as a flexible barrier between the operator and the enclosure.
The most suitable design must balance hand anthropometry, movement, grip and dexterity with the containment, protection, durability and process requirements of the application.
Human factors should be applied using engineering judgement, considering the task, user population, frequency, duration and consequences, rather than treating every recommended value as an absolute design limit.