LDS Methodology
Logical Design Structure (LDS) — PSI’s foundational engineering methodology created by Lew VanKuiken in 1988. Organizes all engineering information around three pillars: Recordable, Re-usable, Retrievable.
What is LDS?
LDS (Logical Design Structure) is a comprehensive engineering project and product management methodology created by Lew VanKuiken in 1988 at PTI (Progressive Technologies Inc., now Progressive Surface). Originally focused on organizing engineering designs and drawings, LDS evolved into a holistic strategy encompassing quality, efficiency, and continuous improvement across the entire organization.
The core objective: organize and manage information so that it has the most value to the organization, which in turn provides the most value to customers.
Key Insight: LDS transforms custom engineering from a “reinvent the wheel” approach to a “build on proven foundations” model.
The Three Pillars
| Pillar | Description |
|---|---|
| Recordable | All information is captured and stored systematically |
| Re-usable | Products and knowledge are leveraged across multiple projects |
| Retrievable | Information is easily found when needed |
The Business Case
| Challenge | Without LDS | With LDS |
|---|---|---|
| Knowledge Loss | Designs recreated; lessons forgotten | Permanent product database; institutional memory preserved |
| Inconsistent Quality | Variable outcomes project-to-project | Standardized, tested building blocks ensure reliability |
| Schedule Delays | Extended design cycles | Re-use of proven Products accelerates delivery |
| Cost Overruns | Engineering hours on solved problems | Focus resources on new challenges only |
| Customer Expectations | Unclear acceptance criteria | RAC document defines success upfront |
The Six Phases (The “6 Ds”)
Every PSI project follows six phases from customer need to delivered solution:
DEFINE --> DESIGN --> DOCUMENT --> DEVELOP --> DEMONSTRATE --> DELIVER
| Phase | Purpose | Key Deliverable | Primary Owner |
|---|---|---|---|
| 1. Define | Establish customer requirements and scope | SLDS Index, Quote | Sales, Proposal Engineering |
| 2. Design | Create technical solution using Products | LDS Index, Engineering Drawings | Project & Design Engineering |
| 3. Document | Record all information for build and service | ECNs, BOMs, Procedures | All Departments |
| 4. Develop | Build and test the machine | Assembled, Tested Machine | Manufacturing, CSS |
| 5. Demonstrate | Prove functionality via customer acceptance | Signed RAC, Punch List | Customer Support Services |
| 6. Deliver | Ship machine with documentation | Final Manuals, Shipped Machine | Shipping |
Key Principle: Documentation runs continuously through all phases — it is not an afterthought but integral to the process.
Cross-reference: manufacturing implements these phases in PSI’s current build pipeline.
The Product Concept
LDS Definition of “Product”
In LDS, a Product has a specific technical meaning different from common usage. A Product is:
- A standardized, reusable building block that has been designed, built, and tested
- Stored in a permanent database for future use
- The foundation from which machines are quoted, designed, manufactured, and tested
- NOT a customer deliverable — it is an internal component
Products vs Projects
| Concept | Definition | Example |
|---|---|---|
| Product | Reusable building block stored in database | A standard spindle positioning unit |
| Project | Specific customer engagement with scope, timeline, budget | Job 2374 — Blast room for Aerospace Co. |
A Project uses multiple Products (combined with custom design) to create a customer machine.
Why Products Matter
| Traditional Approach | LDS Product Approach |
|---|---|
| Design each project from scratch | Select proven Products from library |
| Test each design anew | Products pre-tested and validated |
| Documentation created per project | Product Documents carry forward |
| Knowledge lives in engineers’ heads | Knowledge embedded in Product database |
Result: ~82% reuse rate at the PHYS. level, with first-time parts showing 1.09x higher quality cost.
Entity Hierarchy
LDS organizes engineering information in a strict hierarchy:
FACILITY (Complete machine / top-level installation)
+-- ASSEMBLY (Major assembled components)
| +-- MODULE (Reusable functional units)
| | +-- PRODUCT (Standardized building blocks)
| | +-- COMPONENT / PHYS. (Individual physical parts)
| +-- PRODUCT
+-- ASSEMBLY
+-- ...
Each level has its own drawing numbers, BOMs, and documentation. See BOM Structure for how this maps to the current BOM system.
Numbering Systems
| Type | Format | Description |
|---|---|---|
| Project Number | xxxx (4 characters) | Unique project identifier |
| Product Number | nnnnnn (6 digits) | Unique Product identifier |
| Physical Number | nnnnnn (6 digits) | Drawing number for physical components |
| ECN Number | nnn (3 digits) | ECN file number (001-998; 999 is template) |
The serial hundred-block
The facility takes the machine serial plus 00, and every assembly, module, product and document
for that machine is numbered inside the serial’s hundred-block. Serial 3624 owns 362400-362499.
Slots N0-N9 belong to assembly 0N — so a machine with a second process assembly at slot 04
carries that assembly’s modules at 40-49. Assembly slots are 01-09 (01 cabinet, 02 reclaim or
air handling, 03 controls, 04 second process, 08 spare parts, 09 documentation); reference documents
sit at 90-99 under assembly 09; product and drawing pairs fill the rest of the range.
Because the number is serial-local, two machines’ equivalent modules always carry different numbers — that is the scheme working as designed. At assembly and module level the name is the only identifier comparable across machines. Full detail and the fleet-wide consistency audit are in LDS Index Structure.
Key Documents
LDS Index
The master project organization document, one per project at
K:\PROJECT\<project>\lds\<project>lds.xlsm. The current macro-enabled workbook has five sheets:
| Worksheet | Purpose |
|---|---|
| Index | The BOM tree — every assembly, module, product and document with quantity, parentage and release date |
| DrawingList | The flat 100-slot number block for the machine’s serial |
| Gantt | Overall project schedule and milestones |
| Project Release | Form for releasing to purchase/manufacturing |
| Project Info | Project name, customer, serial, engineers, order date, and the template’s revision history |
Historical note: older LDS documentation describes a seven-worksheet Lotus file (
xxxxlds.wk4) with separate Job Summary, Controls, Mechanical and Macros sheets. The workbook has since been consolidated; the Excel template in use dates from 2019 and its own revision log runs from May 2019 to Oct 2025.
For the slot-numbering rule, the fleet-wide audit and the quote-side (SLDS) column layout, see LDS Index Structure.
SLDS Index (Sales LDS Index)
Preliminary product index created during the proposal/sales phase by Proposal Engineering. Used as the starting reference for the full LDS Index. See also terminology.
ECN (Engineering Change Notice)
Formal document authorizing changes to released drawings. Uses change codes 1-6 to classify the type of change. See ECN Process for the current workflow.
RAC (Runoff Acceptance Criteria)
Defines what the customer must accept during runoff testing. Uses V/D/M markers:
- V = Verify — Item requires verification/confirmation
- D = Demonstrate — Item requires demonstration to customer
- M = Measurement — Item requires measurement
Project Yellow Book
Physical yellow binder containing all project documentation across Sales/Proposal, Engineering, Customer Service, and administrative sections. Created by Proposal Engineering, passed to Project Engineering at handoff, filed in Library after completion.
Project Lifecycle
A condensed view of how a project flows through LDS:
Customer RFQ --> Proposal (SLDS) --> Handoff --> Startup (LDS Index) -->
Design --> Releases --> Manufacturing --> Runoff (RAC) --> Delivery
Key Milestones
| Stage | Key Activities |
|---|---|
| RFQ / Proposal | Requirements gathering, SLDS creation, quoting |
| Project Handoff | Transfer from Sales/Proposal to Engineering; Yellow Book handed off |
| Project Startup | LDS Index created, GANTT chart built, customer contacted |
| Design & Release | Drawings created, Products selected/designed, partial releases to manufacturing |
| Manufacturing | Fabrication, assembly, wiring per released drawings |
| Runoff | Customer acceptance testing per RAC; Punch List resolution |
| Delivery | Final documentation, packing, shipping |
Cross-reference: manufacturing describes each stage in detail with current tooling.
Roles & Responsibilities
| Role | Primary Responsibilities |
|---|---|
| Sales | Customer relationship, quotes, handoff coordination |
| Proposal Engineering | SLDS creation, technical quoting, scope definition |
| Project Engineer | LDS Index, GANTT, releases, ECNs, RAC, customer communication |
| Design Engineer | Engineering drawings, BOMs, Product documents |
| Chief Engineer | Technical leadership, release/ECN approval authority |
| Manufacturing | Building the machine per drawings and work orders |
| CSS (Customer Support Services) | Testing, runoff, punch list, customer training, shipping instructions |
| Shipping | Packing and delivering the machine |
Integration with Modern Systems
LDS concepts map to PSI’s current technology stack:
| LDS Concept | Current Tool | Notes |
|---|---|---|
| LDS Index / GANTT | Project management tools | Scheduling, tracking |
| Engineering Drawings | SolidWorks + PDM | Version control, approval workflows |
| Product Database | AFTEC ERP (UniData) | BOM, part master, job costing |
| ECN Process | ENG.CHG.1287 table | Digital change tracking |
| Quality Tracking | Redbook system | Issue tickets, root cause analysis |
| Design Reuse Metrics | Redbook Analytics Dashboard | Reuse rate, learning curves |
| Product Documents | File server / PDM | Specifications, test plans |
See data-brain for full data and system documentation.
Version History
| Reference | Document | Date |
|---|---|---|
| LDS 1.0 | Introduction to LDS System | 1993-10-06 |
| LDS 3.0.1 | Project Management Guidelines | 1997-09-15 (revised 2005-04-25) |
| LDS 3.1.1 | LDS Index & GANTT Chart | 1997-09-29 |
| LDS 3.1.2 | Engineering Change Notices | Current |
| LDS 3.4 | Runoff Acceptance Criteria | Current |
| LDS 3.5 | Machine Test Plan | Current |
| LDS 3.7 | Service Manual | Current |
| LDS 3.9 | Project Yellow Book | Current |
| LDS 4.2 | Physicals/Products | Current |
| LDS 4.3 | Product Documents | Current |
Related Pages
- manufacturing — Current build pipeline implementing LDS
- terminology — PSI vocabulary including LDS terms
- about — Company overview
- lds-index-structure — The drawing-list workbook, the slot map, and a fleet-wide audit of all 289 completed builds
- psiall-architecture — Technology stack and .NET architecture
- dashboards — Quality dashboards and metrics
Last updated: September 2026