Design and Implementation of Laser Marking with OCR/OCV Vision Inspection System Stephany Serrant Hernández Master in Manufacturing Engineering Advisor: Dr. Carlos González Industrial and Systems Engineering Department Polytechnic University of Puerto Rico Abstract  The laser marking process is aimed to Cobalt Chrome (CoCrMo) and Titanium (Ti) create a permanent identification and/or products go through laser marking process using descriptive information on the surface of metallic multiple Laser Marking systems, such as Laser spinal implants to provide full traceability for the Telesis, which uses fiber laser technology and products being manufactured at Medtronic Spinal Electrox Cobra which uses lamp diode pump Humacao. The process, as its name implies, utilize technologies. In addition, products identification a laser equipment to produce the required tags are also marked using Rofin Marking System. reference marks. Products are marked with their All marks are 100% visually inspected during respective size, lot number and part number. routine manufacturing activities as required per Identification tags are also laser marked for prints specifications which guarantees that marking product identification. In addition, products are information, location, and legibility requirements 100% inspected during routine manufacturing are met. activities to guarantee that marking information, This research project was focused in designing location and legibility are met per print and implementing an integrated Laser Marking and specifications. The DMAIC methodology was used Inspection System. as part of this research project to improve and optimize the Laser Marking and Inspection PROBLEM STATEMENT manufacturing process. DMAIC is a methodology Current marking and inspection system are used for process improvements using Six Sigma. performed separately in different equipment under DMAIC is an acronym that stands for the five different processing stages. This requires more phases of this process: Define, Measure, Analyze, equipment, location space, processing time, Improve and Control. different operators and multiple transactions in the Key Words – DMAIC, Inspection, Laser, manufacturing system. In addition, actual laser Metallic Spinal Implants, Surface, Traceability. marking equipment requires several adjustments for the processing of different products and generate INTRODUCTION high processing scrap for the instability they The laser marking process [1] is aimed to present. There is a high number of units scrapped create a permanent identification and/or descriptive daily in these equipment’s for incomplete laser, information on the surface of metallic implants to laser illegible and laser mark out of position. The provide full traceability for the products being goal of this project is to reduce this scrap and have manufactured at Medtronic Spinal Humacao. The an integrated system that performs both Marking process, as its names implies utilize a laser and Inspection. In order of achieve this goal, the equipment to produce the required traceability such DMAIC project methodology will be used to as the part number identifier, the lot number, size, evaluate the current process and determine material and Medtronic Raising Men (where optimum process improvements along the process. applicable). RESEARCH DESCRIPTION LITERATURE REVIEW This research is focused on the design and The laser marking process [1] is aimed to implementation of a Laser Marking System with create a permanent identification and/or descriptive Optical Character Recognition and Optical information on the surface of metallic spinal Character Verification (OCR-OCV) Vision implants to provide full traceability for the Inspection that will perform laser marking and laser products. The process, as its name implies, utilize a marking inspection operation for multiple products laser equipment to produce the required reference among Humacao Spinal products. System will be marks. Products are marked with their respective able to mark and inspect products for which size, lot number and part number, among others. In processing will require a fixture design to some cases, laser marking may be used to create accommodate the part and provide consistent and reference marks or measurement graduations on repeatable positioning during the process. Laser products to facilitate use by the customer. Laser Marking and Marking inspection will be performed marking process [2] occurs when a beam interacts with OCR-OCV algorithms from their integrated with the surface of a material and slightly alters its machine vision solution within the same laser properties or appearances without engraving the marking equipment. The integrated machine vision material. This process is performed by moving a solution also provides the system the capability to low-powered beam slowly across the material using perform axis adjustments or marking pattern the method of discoloration. The discoloration is a orientation (rotation and displacement) to always method that creates high-contrast marks without mark the part at the specified location. To penetrating the material. Then the laser heats the accommodate different products and different material and causes oxidation under the surface and geometries the machine will have an X, Y and Z turns the material black. The laser then applies low linear motion axes, will provide a docking for temperatures to metal to anneal the surface. This rotation capabilities to accommodate the variability process is done without penetrating the surface of of products currently manufactured at Humacao the metal. Spinal. ILT Laser Marking System with OCR-OCV RESEARCH OBJECTIVES The ILT Laser Marking System with OCR- OCV Vision Inspection will perform laser marking This project aims to achieve implement an and laser marking inspection operation for multiple integrated laser marking and inspection system. products among Humacao Spinal products. The This system will allow more precise marking system will be able to mark and inspect products location and contribute towards laser scrap for which processing will require a fixture design to reduction. In addition, it will reduce equipment, accommodate the part and provide consistent and reduce manufacturing usage space, reduce operators repeatable positioning during the process. The and processing time. Laser Marking and Marking Inspection will be performed with OCR-OCV algorithms from their RESEARCH CONTRIBUTIONS integrated machine vision solution within the same This project seeks to increase laser processing laser marking equipment. The integrated machine output by reducing scrap transaction and processing vision solution also provides the system the time. In addition, reduce equipment space, which capability to perform axis adjustments or marking could further on be used for increasing pattern orientation (rotation and displacement) to manufacturing processing capacity. always mark the part at the specified location. To accommodate different products and different geometries the machine will have an X, Y and Z DMAIC Methodology linear motion axes, will provide a docking for DMAIC is a methodology used for process rotation capabilities to accommodate the variability improvements and process optimization using Six of products currently manufactured at Humacao Sigma. It is a data-driven quality strategy used for Spinal. process improvements. DMAIC is an acronym that stands for the five phases of this process: Define, Measure, Analyze, Improve and Control (See Figure 3). Figure 1 Figure 3 ILT System DMAIC Methodology System is required to laser mark and inspect In the Define phase, the customer, team, plan parts as required. In general system is required to and charter are defined. The problem/opportunities be able to: are stated, and the projects expectations are also  Provide Means to Verify Part Presence defined. In addition, the requirements to achieve the  Provide Means to Laser Mark Part and Inspect desired output are established. In the Measure o Provide Operator Interface by Means of phase, data is collected of the process and HMI, PC or any other visual mean document in order to have a baseline data narrow o Provide Safety features for Operation for the project focus. The analyze phase, the data (Guards, Interlocks, Emergency Stop, etc.) collected is analyzed to determine possible root o Provide Access Levels for Protection causes and identify and remove wastes from the (User-Password Controlled) process. In the Improve phase, solutions are o Provide Means to Make Program/Job Files generated and evaluated to optimizes and improve per Part Number/Model or family. the opportunities identified. Finally, the Control phase, the projects benefits are validated. METHODOLOGY In order to achieve the goals for this project a systematic approach will be used. This project seeks to increase laser processing output by reducing scrap transaction and processing time. In addition, reduce equipment space, which could further on be used for increasing manufacturing processing capacity. Since the purpose of the project is to improve the output of laser marked Figure 2 units, the DMAIC methodology will be used. ILT Process Summary DMAIC is a methodology used for process improvements and process optimization using Six laser marking equipment requires several adjustments for the Sigma. It is a data-driven quality strategy used for processing of different products and generate high processing scrap for the instability they present. There is a process improvements. DMAIC [3] is an acronym high number of units scrapped daily in these equipment’s for that stands for the five phases of this process: incomplete laser, laser illegible and laser mark out of Define, Measure, Analyze, Improve and Control. position. The goal of this project is to reduce this scrap and For the define phase, a project charter will be have an integrated system that performs both Marking and Inspection. In order of achieve this goal, the DMAIC project used to preliminary define the scope of the project, methodology will be used. goals, objectives, personnel involved, roles and TEAM MEMBERS responsibilities, timeline, stakeholders, and Key Stakeholders Members Names structured the project. In the Measure phase scrap Project Manager Carlos Curet unit’s data will be collected from December 2017 Manufacturing Manager Luis Colon Quality Engineer Stephany Serrant the start-up of the New Product Introduction up to Manufacturing Engineer Jonatan Rosario May 2018, to be representative of the process, SME Carlos Gonzalez using the different laser marking defects reject Project Sponsor Alberto Rivera codes, such as incomplete laser, laser illegible and Additional Resources Members Names laser mark out of position. For the Analyze phase, Environmental, Health Mildred Pizzaro the data collected will be analyzed to determine top & Safety Representative offender reject code and compared with the data PROJECT RISKS Risk Low Medium High from the new laser system. This process data will Location Restrictions X be continually evaluated throughout the Equipment Availability X improvement and control phase to determine the PROJECT TIMELINE project’s success. Key Milestone Target Date Start Date 15-MAY-16 RESULTS AND DISCUSSION Purchase of Equipment 31-JAN-18 For the Define Phase of this project, a project Installation of 25-FEB-18 Equipment charter was used to define all the deliverables, Modification of 1-APRIL-18 focus and goals of the project (See Table 1). Procedures Table 1 Training 15-APRIL-18 Project Charter Completion Date 30-APR-18 PROJECT TITLE PRELIMINARY BUDGET Design and Implementation of Laser Marking with The preliminary budget for this project is of 500K. OCR/OCV Vision Inspection System. BUSINESS CASE In the Measure phase scrap unit’s data will be This project has the intent to potentially decrease the scraps in manufacturing due to laser marking defects and increase collected from December 2017 the start-up of the process output. New Product Introduction up to May 2018, to be GOAL STATEMENT representative of the process, using the different The goal for this project is to reduce manufacturing laser laser marking defects reject codes, such as marking scraps by June 2018. incomplete laser, laser illegible and laser mark out SCOPE In Scope: Laser Marking Process, Out of Scope: All other of position (Refer to Table 2). This data will be Processes. analyzed to determine the mayor offender of the PROBLEM/OPPORTUNITY STATEMENT laser marking defects. In addition, the process Current marking and inspection system are performed output will be compared from the actual process to separately in different equipment under different processing stages. This requires more equipment, location space, when the new implemented system is incorporated processing time, different operators and multiple into the Manufacturing operations. For the new transactions in the manufacturing system. In addition, actual implanted system, the scrap reject code for defects deliverable of the project’s implementation tasks associated to the Laser Marking is and deadlines (See Table 3 & Figure 5). “Msd:ILTVisionSystem:InspectionFail”. Since this Table 3 new equipment is dedicated to a New Introductory Gantt Chart Data Product, the data was filtered for that specific Start Duration No Action Items End Date product. All other reject codes shown in Table 2 are Date (Days) associated to the Legacy Laser Machines. Figure 4 System Concept shows that the top offender reject code associated 1 5/15/2016 5/30/2016 15.00 Quote to the Laser Scrap is Mark out of Position. This reject code is mainly seen associated to the setup Capital 2 Authorization 5/29/2016 6/28/2016 30.00 and adjustment made to the equipment when Request changing from different part numbers or product families. Current Laser Equipment are sensitive to 3 PO in Place 7/1/2016 7/31/2016 30.00 parameter changes, and when changing from part Project Kick off @ number or product families, several adjustments 4 9/15/2016 9/30/2016 15.00 supplier need to be made for the parts to meet with their System and print specifications. This causes an increase in 5 Fixturing Solutions 10/17/2016 12/16/2016 60.00 Mark out of Position of the parts. Design Acceptance Table 2 Factory Controls Scrap Data 6 Communication 3/15/2017 4/14/2017 30.00 Acceptance Custom Design 7 Specifications 7/15/2017 8/14/2017 30.00 Acceptance Applications 8 Design 9/13/2017 10/13/2017 30.00 Specification Developing 9 Processing 11/5/2017 12/20/2017 45.00 Parameters Development of 10 Vision Inspection 11/5/2017 12/15/2017 40.00 application FAT Readiness 11 1/10/2018 1/20/2018 10.00 (Milestone) FAT execution / 12 1/21/2018 1/31/2018 10.00 Acceptance Equipment 13 2/2/2018 2/15/2018 13.00 Shipment SAT Testing and 14 2/25/2018 43160 4.00 Commissioning Equipment/Process 15 Validations/ 3/1/2018 4/30/2018 60.00 Figure 4 implementation Top Offender Laser Scrap For the implementation phase of this project a Gantt Chart was developed to define all the laser processing output by reducing scrap transaction and processing time, so far from the data obtained, the ILT System has demonstrated to be capable for its intended used and fulfil the business desired output. In addition, reduced equipment space, which could further on be used for increasing manufacturing processing capacity. REFERENCES [1] L. Gillespie, Design for Advanced Manufacturing: Technologies and Processes: Laser Marking and Figure 5 Engraving, McGraw-Hill Professional, New York, USA, Project’s Gantt Chart 2017. From the data presented in the DMAIC [2] H. Geng, “Laser Materials Processing Manufacturing”, Measure Phase, shows a significant reduction in the Engineering Handbook, 2nd ed., McGraw-Hill Professional, scrap from the Laser Marking Operation performed New York, USA, 2016. under the ILT System. Since new ILT System was [3] J. Juran. “Lean Techniques: Improving Process implemented on April 2018, there is not much data Efficiency”, in Juran’s Quality Handbook, 6th ed. 2010, pp. presented in order to compare with past data. 327-353. Although, from when it was implemented up to May 2018, only sixty-four (64) units were detected to be scrapped from the new laser system (Refer to Figure 4). All units where physically inspected to determine potential root causes for these scrap transactions. Units presented Laser Marking that met with print specifications, but the Vision System required to be trained and expand the Vision Field and failed the inspection. They did not present a product laser mark defect, but operators still performed the scrap transactions. As a mitigation, awareness was generated to operators in order for Engineering to be able to perform the training transactions required by the system on the Vision Inspection System. This data presents, that when laser mark is being performed under this new system, the scrap transactions present to be in control and they have been significantly decrease. This is due to that the ILT system is a more precise Laser Marking System. CONCLUSION Since this project is has been recently implanted on site, there are not much data results for the improvement and control phases. Although, the expected result from this project is to increase