Erdem Yilmaz

Senior manufacturing engineer. About eight years taking mechanical and electromechanical products from prototype to volume production: build plans and readiness criteria, automated test stations, fixtures and process controls, design for manufacturing reviews, supplier change control, and the root cause work that keeps a line running. The sections below are organised by what I do rather than by where I did it.

New product introduction

  • Owned manufacturing engineering for a residential heat pump thermal battery built at contract manufacturers. Took it from prototype and pilot builds through qualification builds to volume production release in six months, and ran the development of a new-generation design into production alongside it. Owned the build plans, the readiness criteria, and the call on when the line could run without an engineer standing next to it. Harvest Thermal
  • Drove line readiness and design-for-x validation across two HVAC product generations. Managed a cut-in that had the line building two configurations at once: two sets of work instructions, two fixture states, and a sequencing plan that kept them apart on the floor. Gradient Comfort
  • Developed an air-source heat pump water heater from concept through validation, including the fixtures and instrumented stations the validation ran on. Vaughn Thermal

Test development

  • Built automated leak and functional test stations for sealed assemblies: pressure-decay measurement through calibrated transducers and solenoid sequencing, pass/fail logic in Python on OpenHTF, limits held in versioned configuration rather than in code, and every result logged per serial number. Defined the coverage and acceptance criteria by tracing each limit to a functional requirement rather than to what the instrument could resolve. Cut diagnosis and repair time per failed unit by roughly two thirds, because a technician could see which step failed and by how much instead of starting from a symptom. Harvest Thermal
  • Designed and built the fixtures and instrumented stations for evacuation, pressure test, and refrigerant charging on a heat pump water heater program, including vacuum verification and mass-based charging. Vaughn Thermal
  • Designed the inspection fixtures used to verify assemblies before they moved downstream. Gradient Comfort
Architecture of an automated test station Left to right: a fixture holding the device under test; instruments (pressure transducer, solenoid manifold, power supply); an OpenHTF sequencer in Python that receives limits from a versioned configuration file shown above it; a pass or fail verdict; and a result record per serial number written to storage. Two notes: limits live in configuration, not code; the result is written before anything else can fail. Fixtureand DUT Instruments pressure transducersolenoid manifoldpower supply OpenHTFsequencer in Python Limitsversioned config Verdictpass / fail Resultper serialnumber to storage Limits live in configuration, not in code: a limit change is a reviewed file revision, not a code release. The result record is written before anything else can fail, so no tested unit is ever unaccounted for.
How I lay out a test station. The two notes are the design opinions; the rest is plumbing.

Process, tooling, and fixtures

  • Designed assembly, brazing, and inspection fixtures in SolidWorks and deployed them to the assembly line, then wrote the SOPs and field-service instructions the technicians worked to. Gradient Comfort
  • Led Process FMEAs on critical assembly and test operations and implemented the controls that came out of them: torque control, go/no-go gauges, poka-yoke fixturing, and SPC monitoring on the parameters that moved. Trained the contract manufacturer's line technicians on each control, on their floor, on their shift. Harvest Thermal
  • Led a value stream mapping project across a pressure-vessel production area that cut manufacturing throughput time by about 15 percent. Hubbell Electric Water Heaters
The 3-2-1 locating principle Top view of a rectangular part resting on three support pads (datum A), pushed by clamps against two pins along its bottom edge (datum B) and one pin on its left edge (datum C). Arrows show clamping forces directed toward the locators. Six degrees of freedom are constrained exactly, and the fixture datums match the drawing datums. AAA BB C Three pads: datum Arest, remove 3 DOF Two pins: datum Bedge, remove 2 DOF One pin: datum Cend, remove 1 DOF Clamps push towardthe locators, neveragainst a free face. Top view
The principle behind every fixture I have designed: constrain six degrees of freedom exactly once, and make the fixture's datums the drawing's datums.

Design for manufacturing and assembly

  • Ran DFM and DFA on two product generations and validated manufacturability and assembly flow on the line rather than on paper; assembly waste fell by about a fifth and production yield rose. Ran large-assembly reviews in SolidWorks, with interference checking and tolerance stack analysis, to catch fit and clearance problems before a physical build. Gradient Comfort
  • Owned sheet metal design and one complex injection moulded part from design through tooling and first articles, working the parts through waterjet cutting, forming, and moulding. Gradient Comfort
  • Led design communication with contract manufacturers, running DFx reviews in CAD and DFM tools, and performed tolerance stack-up analysis to drive the design changes that made assembly repeatable. Vaughn Thermal
  • Applied DFMA principles to part designs and released production-ready drawings. Hubbell Electric Water Heaters

Supplier and contract manufacturer engagement

  • Owned engineering change orders and supplier change control. Released BOMs, drawings, SOPs, work instructions, and test procedures with revision traceability in PLM, and planned cut-ins and stock use-up so that a design change stranded no inventory and stopped no line. Harvest Thermal
  • Ran root cause and corrective action on supplier quality escapes: quality notifications, returns, and long-term corrective action rather than containment alone. Raised incoming acceptance substantially over the program. Caught a long-lead part built to the wrong revision before it was received, which prevented a line stop. Harvest Thermal
  • Ran design and manufacturability communication with contract manufacturers through development. Vaughn Thermal

Root cause and quality

  • Raised first-pass yield on a pilot line to over 90 percent. There was no manufacturing execution system and no ERP, so the first step was a data pipeline in Power BI built from what the line actually produced; then defect modes ranked by frequency and by the cost of the rework each caused; then the top contributors root-caused one at a time. Rework halved and weekly output tripled. Harvest Thermal
  • Root-caused recurring field failures using 8D and closed the loop in the design rather than in the field, redesigning the affected subsystems. No recurrence after the fix shipped. Gradient Comfort
  • Investigated a purchased pump that seized progressively in service, working from field symptoms and returned units back to the physical mechanism. Gradient Comfort
The yield improvement loop Five boxes connected in a loop: capture defect data at the station; rank defect modes by frequency and by rework cost; root-cause the top contributor; implement a control at the operation where the defect is created; re-measure; and back to capture. A note says the loop runs on one contributor at a time. Capturedefect data at the station Rankfrequency and rework cost Root-causethe top contributor Controlwhere the defect is created Re-measuredid the mode disappear? One contributor per pass. The data pipeline comes first; without it, ranking is opinion.
The method behind the yield work. The defect names belong to the employer; the loop is mine.

Tools and methods

SolidWorks and SolidWorks PDM, Arena PLM, KiCad, Python, OpenHTF, Power BI, GD&T drawing interpretation, sheet metal design, tolerance stack analysis, Process FMEA, 8D and 5-Why, SPC and capability analysis.

Education

MS Mechanical Engineering, University of Bridgeport. First Place, Graduate Papers, ASEE Northeast Section Conference, 2018. BS Mechanical Engineering, Selcuk University.

Why I write the courses

Most of what is above I learned after the drawing was released: in supplier reviews, on the production floor, and in the meetings where a late change gets priced. None of it was secret, but none of it was collected anywhere a junior engineer could read it before the first ramp. The courses collect it, with the reasons attached and the sources cited, so the next engineer meets fewer surprises.

How the courses are made

Every real-world example, statistic, and standard is checked against a source before it is written, and the source is cited so you can read it yourself. Numeric design rules come from published manufacturer design guides, standards bodies, and industry associations, paraphrased rather than copied. Where a claim could not be verified, the course says so rather than attaching false precision. Examples with invented numbers are labelled illustrative. Units are metric. The courses contain no information from my employers; this page describes my own work in general terms and nothing of theirs.

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Licence

Course content (text, tables, diagrams, exercises, quizzes) is offered under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 unless a course states otherwise. Site code is MIT licensed. Cited sources remain the property of their publishers.

Contact

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