Multi-purpose production test unit solution

Inkjet print head test station re-configurable to fulfil multiple roles on the production line.

The Skills Required

A number of key features had to be integral to the design.
- Ease of maintenance
- User safety protection
- Tester adaptation for multiple product lines & multiple test station functions.
- A user experience familiar to production line operators

Central to the hardware design was striking the right balance between use of appropriate off-the-shelf solutions and bespoke electronic pcb design. Configurability, cost, ease of maintenance and performance were central to this choice.
Careful connector choice and sacrificial board design helped guarantee a long term solution that was easy to use and maintain.

By selection of an appropriate DAC solution with built-in API it was possible to make significant engineering savings by avoiding the need for embedded software design.
Software effort was focussed on a highly configurable, easy to use PC interface, developed on a fast turn-around feature-rich UI development environment.

The Brief

A global provider of industrial inkjet drop-on-demand printers needed a production test solution that could support multiple legacy and future products through the various stages of their production process: part assembly module test; end-of-line; and rework station.

The flexibility requirement and high voltage nature of the product-under-test demanded both engineering level and test operative level distinct logins. This would allow a qualified production engineer to re-configure the test solution for different test stations and products, whilst presenting a simplified semi-automated interface for safe high-throughput testing on a production shift.

The individual test level requirements included a combination of continuity testing, electrical & pneumatic functional testing and high voltage testing. Test results were to be stored in a server database registered against a barcode, scanned at each stage of the production process.

 

The Solution

Fen began this work by developing the test specifications in co-operation with client production engineers. Knowledge of the products’ test requirements and legacy test equipment rested with a number of the client’s engineers. Once this consolidation process was complete, the next challenge was to specify and design a production tester that could be dynamically re-purposed, to meet all product test requirements, at all stages of the production process. Care was taken to follow the look and feel of legacy test solutions so as not to alienate production line workers. A series of interviews and workshops helped in this process.

Fen designed and manufactured a test unit that used a combination of off-the-shelf DAC & configurable IO modules, and bespoke analogue interface PCB’s. An FMEA analysis was undertaken as part of the process, resulting in a number of safety & poke-yoke features. In addition, a number of easily replaceable sacrificial elements were added to the design, to maximise tester lifetime on the production line, with minimal maintenance effort.

Fen created a Windows application to exchange control commands and data with the embedded test hardware over a USB port. The application’s admin mode allowed the definition and scripting of command & control test sequences, including pass/fail thresholds and user instructions. The admin user could then set the test UI into any one of its user modes appropriate to the installed test station.

In the chosen test user mode, the test operative would be guided through a predetermined sequence, resulting in a clear pass/fail indication and appropriate error codes, with all test results stored in a network database against pre-scanned barcode ID.

After completing design verification testing, Fen engineers delivered and installed a number of test stations on the client’s production line. This included initial handover training and longer term support for maintenance and feature enhancement.

 

 

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