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Sample Audit
Objectives and Scope
A site audit was performed by Dave Roesler of TRI-C Design. The purpose of the audit was to review and evaluate the turnaround and quality of ABC Company’s current tooling process. The tooling process includes the process from the receipt of customer data to the tools and data produced by the CAM Department. From this evaluation, solutions were to be identified that would help improve both quality and turnaround.
Methodology
The site audit was performed by observing the tooling process and interviewing individuals from many different levels and departments. Individuals interviewed include:
- CAM department
- Product engineers
- Process engineers
- Management (engineering, sales, production, etc.)
- Tool vendors
General Findings
The findings of any research are only as accurate as the data on which the findings are based. The conclusions of this study must, of course, take into account that my direct observations occurred during a time span of 3 days.
The following is a summary of my findings:
- The first article process is too slow and does not catch all errors.
- Clarification is needed regarding your photoplotting vendor’s plotting capabilities. It is also not clear whether your photoplotting vendor fully understands all of your current and future requirements.
- CAM errors have not been historically tracked. Therefore, level and severity of errors is ambiguous.
- There is a general lack of standards and documentation for the tooling process.
- The current tooling process is heavily reliant on the experience and expertise of the CAM manager.
- The results from the CAM Department are inconsistent.
- There are insufficient resources in the CAM Department to handle the peak workloads and to provide adequate turnaround for all groups.
- There is a lack of checks and balances in the CAM Department (e.g. DRC, netlist compare, buss verification, etc.)
- Special compensation needs documentation and definition.
Areas for Process Improvement
Based on my observations and interviews, the following process areas need improvement. Although there may be many smaller issues, I chose to concentrate on those that had the most process impact. I present the following suggestions in the spirit of constructive comments, not as criticisms of existing practices.
Phototool Errors
The current tooling process lacks adequate checks and balances to ensure that the circuit data is correct. Specific concerns were raised regarding DRC violations, missed bussing and, to a lesser degree, missing tooling information. These errors are devastating due to the high cost of precision phototools and the loss of turnaround time waiting for replots.
To reduce the number of phototool errors, netlist compare, DRC and buss checking need to be implemented to validate that the circuit data meets all customer and manufacturing design rules, that shorts or opens have not been introduced during the compensation process and that all features are properly bussed. I would also recommend that a final paper plot package be produced which is reviewed by someone other than the original operator. We have found this checking technique to be very effective.
Errors from the CAM Department also need to be monitored to determine which errors occur most frequently. This will allow effort to be focused on those areas that will provide the most improvement.
Inconsistent Results from Operator to Operator and Job to Job
The current tooling process is not documented and, therefore, lacks consistency. It is highly operator dependent and is heavily reliant on the CAM manager’s experience and expertise. There is also a lack of documented standards for the panel that adds to the inconsistencies of the outputs produced.
A consistent, well-documented process needs to be defined. This process will allow for consistency in quality, regardless of the operator, and will allow new operators to be trained quickly. The process must be defined such that the amount of expertise required regarding ABC Company’s process is minimized. The panel standards must also be documented and approved by all departments. These standards provide a baseline for which automation can be written to produce consistent panelization and outputs. It also provides a means to communicate panel changes and additions to all departments.
Special Compensation
The most time consuming item in the tooling process is the addition of the special compensation. Currently, this special compensation is not well defined and is heavily reliant on each operator’s experience and expertise.
The collective knowledge of those that understand the special compensation needs to be documented and the process of applying it needs to be proceduralized. This documentation should include pictures of examples whenever possible. If there are areas of special compensation that are not understood well, specific experiments need to be devised to gain the necessary understanding. The process of applying special compensation needs to be defined in such a way that it does not require any expertise to apply. This definition will provide guidelines to allow operators to apply it consistently and also allows for the possibility of future automated tools.
Turnaround
Most of the complaints regarding turnaround came from the A, B and C groups. In the case of the A group, the turnaround had to do with the amount of time required to apply the special compensation. On some circuits, the comping can take days. In the case of the B and C groups, their tooling needs usually take lower priority. The D groups only turnaround complaint comes when they get a large number of projects in at the same time. All of these circumstances require too much prioritization of work.
To handle the special workload and to allow all product areas to receive adequate attention with minimal prioritization of work, overflow resources must be identified to offload work. To minimize expense, these resources must be temporary resources that are only used when the work is available such as those provided by an outside service bureau.
Automation needs to be investigated to reduce the time consuming, manual process of special compensation. If this process cannot be automated, techniques and processes need to be developed that allow the project to be distributed among multiple operators to reduce the overall turnaround time.
Photoplotting vendor
Many issues were raised with regards to the artworks supplied by the phototool vendor. These issues included turnaround, feature tolerance, edge definition and coating options. Concerns were also raised because the photoplotting vendor is ABC Company’s only source for large, high tolerance phototools.
It was difficult during the interview process to determine whether the photoplotting vendor isn’t meeting ABC Company’s current needs or whether there is only a perception that the photoplotting vendor isn’t meeting ABC Company’s needs. Turnaround was confusing because, in many cases, individuals lumped CAD and first article in the overall turnaround time. There is also a lot of misinformation regarding the photoplotting vendor’s capabilities and plotter specifications. I would recommend that ABC Company document its current requirements and those of the foreseeable future to present to the photoplotting vendor. ABC Company should also require the photoplotting vendor to document its capabilities and services relative to ABC Company. This eliminates any confusion or misconceptions with either party.
I also would recommend that ABC Company identify a consistent group who is responsible for the ABC Company/photoplotting vendor relationship. This group must include technical process engineers and one high-level business manager. The process engineers would be responsible for documenting and communicating ABC Company’s technical requirements. The business manager would be responsible for communicating the business needs regarding price, turnaround, quality, etc.
Finally, an investigation should be performed to determine whether ABC Company should consider purchasing their own plotter and whether adequate second sources exist.
First Article
Concerns were expressed regarding the first article process. Specifically, turnaround is too slow and not all problems are caught because of the sampling process used.
The current methods used for first article are not sufficient for the density and complexity of artworks being generated, especially for the group A. A method needs to be developed which 100% inspects the artwork. I recommend that ABC Company investigate use of AOI for artwork inspection. The OGP would still be used to inspect a single image site to verify that it meets customer spec with regards to line widths, etc. The AOI would be used to ensure that the all sites are correct (i.e. 100% inspection) by comparing the artwork to the original CAM data. By comparing the artwork to this data, you can locate any site that has a defect. This method will locate defects on a single image site that is not sampled by today’s techniques.
Miscellaneous
- The data received by the tool and die vendor requires cleanup to make geometry connect end to end. This is caused by a bug in the DXF output of the revision of CAM software you are currently using. There is an update to the DXF output module that fixes this problem. ABC Company needs to contact the CAM vendor to get the update.
- There are techniques dealing with subfigures that may help with some of the problems that have existed with missing tooling holes. These techniques need to be identified and trained across all operators.
- Standards need to be developed and adhered to within the CAM Department such as layering convention, file and directory naming, etc. This is a requirement if automation is to be developed and used.
- Engineers need to fill out the rout sheets. Many times the information is being filled in by the CAM Department.
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