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Current Special Interest Groups

Welcome to the BGA’s Special Interest Groups (SIG) web area.

Special Interest Groups are a semi-structured group of BGA members with a common interest in a specific area of relevant technology. The purpose of the groups is to provide a forum for BGA members to discuss common problems or topic areas to a common benefit. The outputs for these groups can be to develop more structured research opportunities or to simply address specific topics for the moment in a particular subject area.

A SIG can be initiated by any BGA member who presents a proposal statement where other members share a common interest. As with the research projects the BGA provides an area within the web site for the communication and sharing of documentation within a SIG.

The terms of reference for the initiation and operation of a SIG are provided in the link on this page.

We are proposing to set up a SIG looking at ISO 6336, the gear stress analysis standards.  This is particularly relevant because a revision to ISO 6336 is currently nearing publication.  It is proposed that the first sessions will be chaired by Design Unit, but this has to be decided by the SIG members during the initial telephone conference call proposed for 2 Oct 2018 at 10am. 

There are many problems using the ISO 6336 gear stress analysis.  Using commercial software packages is challenging enough.  Trying to write your own spreadsheet or coding the standard takes it to a different level.

The objective of the teleconference call is to propose what the SIG does and manage its activities.  Examples could include:

  1. A confidential round robin comparison of ISO 6336 analysis results by members.
  2. Load distribution modelling and validation.
  3. Miners sum round robin comparison.
  4. Helix angle factor validation.
  5. Comparison with TCA models.
  6. Running in allowances

The confidential round robin exercise would be a good way of starting this SIG off.  We can propose a geometry and conditions and compare results from different packages and users or find problems with interpretation of the standards for example.

Work from this SIG could inform the ISO TC60 WG6 committee who develop the standard and also identify where the UK needs to do research to support gear stress analysis.

Membership of a SIG is free to BGA members.

Please contact Lindsay and Kirsty at the BGA before 28 September on 0191 2086160 / if you wish to participate in the in the initial conference call and allow time to send you the dial in details and an agenda.  We look forward to hearing from you.

This SIG is chaired by Dr Paul Bradley of Allen Gears.

The Splines SIG is addressing the design, specification, stressing and performance of splines, splined joints and splined couplings. The motivation for the formation of the group is a result of a fairly widely shared opinion that the design and stressing of splines is an area of little standardised methodology where the amount of published information for spline design is very limited. In addition, in areas where some standardisation is available, such as geometry, this information is also lacking some clarity with respect to certain significant features when considering the operating performance of a splined joint, such as accuracy effects etc. General areas of interest are currently related around the following key areas, although this is not intended to be a conclusive or exhaustive list :

  • Spline Geometry
  • Spline Accuracy
  • Spline Stressing and Rating F
  • Fixed and Flexible
  • Spline Joint Design
  • Spline Dynamics
  • Spline Manufacturing Influences/Methods

With this void in generalised spline standardisation and technology in mind, the SIG group is considering these various topics and where appropriate, is pooling information and experience to provide for the formation of more formal BGA research projects.

The SIG has considered failure modes in some detail and will aim at developing something for splines along the lines of the existing BGA Codes of Practice for gears and ANSI/AGMA 1010–E95 Appearance of Gear Teeth – Terminology of Wear and Failure.

If you are interested in the subject matter described here and would like to be involved in the SIG, please contact the BGA at or 0191 208 6160

This SIG is chaired by Dr Rob Frazer of the Design Unit, Newcastle University.

The initial meetings of the Gear Measurement SIG agreed that the highest priority was to arrange some informal measurement comparisons (round robin exercise) to assess the capability of industrial gear measuring equipment. This allows participants to benchmark their own gear measurement capability. Results will be coded for confidentiality.

The SIG members agreed that the selected gears (6 in total so far) had to be full gears and the comparison will involve pitch, runout, profile, helix and tooth thickness measurement. The pilot gear selected to develop the instructions and evaluation/reporting methods is from the Design Unit, National Gear Metrology Laboratory (NGML) at Newcastle University.

Reference data for the Round Robin will be provided by the UKAS accredited NGML. Participants will get a free calibration check of their measuring machine from the UKAS national laboratory.

The results from this survey will allow the SIG members to make informed decisions about their measurement capability and steer future SIG activities.

If you are a BGA member and want to get involved with the gear measurement SIG, please contact the BGA at or 0191 208 6160

A BGA Special Interest Group (SIG) addressing the gear tooth failure mechanism currently known as Tooth Flank Breakage, but also previously described as Tooth Internal Fatigue Fracture (TIFF) and White Etch Cracking has been formed. This SIG is chaired by Dr Paul Bradley of Allen Gears.

The failure mode under consideration is one where gear tooth failure originates (typically on surface hardened gears) at a point below the working surface of the gear tooth at a location generally un-associated with the Hertzian point of maximum shear stress or case/core interface.

The motivation for the formation of this group is a result of a growing identification of this previously uncharacterised failure mode across a range of transmission products, applications and gearing types.

The topic has been raised at an ISO level as an ongoing work item by the committee tasked with addressing standardisation of gear load capacity (ISO/TC60/SC2/WG6). This working group (WG) has recently formally registered the new project as ISO/PWI 19042: Tooth Flank Breakage.

Due to the lack of general awareness of this failure mode and any associated evaluation techniques, this SIG is concentrating on the following topics (although this is not an exhaustive list):

*Sharing of application examples of failure modes fulfilling the basic descriptions

*Definition and physical characterisation of the failure mode(s)

*Discussion of failure mechanism(s) and potential causes

*Discussion and review of applicable design analysis techniques

*Track and discussion of ISO working group activities on the topic

*Practical validation techniques of the failure mode(s)

*Development of design practices or guidelines associated with failure mechanism

With little information or common definition of this failure mode in wider circulation, the SIG is considering the various topics above and where appropriate, is pooling information and experience to provide collaborative advances in the understanding of Tooth Flank Breakage and/or the analysis techniques needed to provide design evaluation.

Further outcomes from the work of this group could stimulate or provide suitable grounding for the formation of more formal BGA research activity.

If you are interested in the subject matter described here and would like to be involved in the SIG, please contact the BGA at or 0191 208 6160