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Lightforce Orthodontics
wi
Work Instructions and Poster Guides
Purpose: To standardize the operation of the DLP printers used for bracket printing.
Scope:
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Train technicians in standard checks and adjustments before starting prints by following a printed checklist attached on every printer door, as well as poster guides pasted in clear view as reminders.
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Improve process control and reduce process variations, leading to lower print failures.
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Allow engineers to find root-cause of printing failure modes due to defined parameters and checks.
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Improve quality control by adding work instructions to QMS and LMS.
List of Bracket Printing Work Instructions:
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1. S65 Bracket Printing Work Instructions for MFG Technicians
2. S65 Vat Cleaning Work Instructions
3. S65 Cartridge Replacement Work Instructions
3. S65 Vat Replacement Work Instructions
Results:
​1. Process control improved as technicians followed the same procedure steps, allowing traceability of root-cause for print failures. For instance, if there was a print fail, engineers could use the Slack workflow to trace back to a probable cause, like incorrect slurry depth setting or poor parallelism.
2. Correct print parameters could be ensured for every print.
3. Technicians had clear instructions of what to do in case of print fails, which improved communication between production and engineering.
4. Cross-training was significantly easier due to appropriate procedure guidance and picture references of correct visual settings.
magellan
Optical Inspection Machine SOP
Purpose: To allow operators of the Magellan V200 optical inspection machine perform slot measurements of brackets accurately and efficiently.
Scope:
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Initial steps were to fully automate the process through a jig and palletization through pattern recognition - this proved to be challenging due to the large variety of slot designs and sizes
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The final workflow adheres to the following steps:
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place a part from each case in each square slot of the jig​
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place the jig on the workstage
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manually jog from one part to the next and take measurements
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A 1/4" acrylic sheet is laser cut to fit into the middle layer of the 3D-printed jig that acts as a transparent slide that can hold the parts while also letting the backlight through for image detection. This allowed easier handling of parts when positioned in each slot of the jig.
Optical Inspection Machine SOP
Results:
​1. Measurement workflow was optimized, producing more accurate and reliable data for slot measurement analysis in DOEs and Out-Of-Line.
2. Measurement time was significantly reduced by 87% (15 mins to 2 mins - depending on how many parts would need to be placed in the jig).
Crucibles
Crucible Disposition Process
Purpose: To reduce frequency of part yellowing when taken through the sintering process
Scope:
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Establish crucible condition to be a determining factor for yellowing of parts
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Root-cause analysis through an experiment to check polarimetry of parts sintered in crucibles of varying conditions - new/old, rigidized/non-rigidized (2x2 matrix)
The experiment results revealed that a higher frequency of yellow parts occurred in the crucibles with broken rear walls. This led to the hypothesis that excess radiant heat from the heat tubes was allowed to flow through the crucibles that were missing rear walls when stacked inside the furnace.
The appropriate rigidization procedure was also developed and deployed to prevent dust accumulation in the crucibles, which was also a contributing factor to poor quality parts, since white alumina dust would bond to parts during sintering, creating rough edges.
Experiment Details
Since no inventory for crucibles existed, a crucible inventory was taken, and crucibles were sorted according to the following:
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​If any of the rear walls or the patient alias in front/back walls are missing, sort them into the "Broken" bin.​
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​Perform a glove test to check for dust. Dusty crucibles would need to re-rigidized and sorted into the "Dusty" bin.
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Appropriate posters were placed at the crucible handling station for technicians to follow this protocol.
Results:
​1. Rate of yellow parts was reduced considerably (unknown stats), due to fewer broken crucibles being used.
2. Rate of dusty parts was reduced significantly (unknown stats), due to rigidized crucibles released into circulation.
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