Mechanical Design
& Machine Development
Machine concepts, detailed CAD, jigs, fixtures, and special-purpose equipment developed around the task.
ENGINEERING WITH PURPOSE
BHA Engineering
HALO Technology
We Engineer
Better Systems.
Engineering consulting, mechanical design,
and manufacturing engineering support.
Practical solutions from concept to production.
BHA Engineering HALO Technology is the engineering brand of CHEONJI INNOVATION.
DESIGN · ANALYZE · OPTIMIZECONCEPT TO REAL-WORLD PERFORMANCE
01 / CORE EXPERTISE
Built on engineering.
Grounded in manufacturing.
Connecting design decisions with materials, machining, assembly, and real operating requirements.
Mechanical Design
Manufacturing Engineering
& Cutting Tool Design
Design for Manufacturing (DFM) and CNC process planning. PCD and SCD cutting-tool design, including single-point diamond turning (SPDT) tools, special ISO tool holders, generating tools, and fine boring tools.
System Analysis
& Engineering Support
Strength, stiffness, and vibration-response evaluation to guide design decisions, prototype development, and production engineering.
ENGINEERING SERVICES
A fresh perspective.
A practical way forward.
Engineering consultation is available for new concepts, existing designs, and machinery improvement projects. We connect requirements and ideas to manufacturable designs and physical products, from concept onward.
Engineering Consulting
& Technical Review
We review concepts and designs, clarify technical constraints, and help define the development direction.
Troubleshooting
& Root Cause Analysis
We investigate mechanical, vibration, machining, and assembly problems to identify likely causes and propose corrective actions.
Reverse Engineering
& Redesign
We examine the functions of existing components and machines and develop redesign options around the project requirements.
DFM
& Cost Optimization
We review manufacturability, assembly, and process choices to identify opportunities to simplify production and reduce manufacturing costs.
Machining Process Optimization
& Process Simplification
We review machining sequences, setups, tooling, and workholding to identify opportunities to shorten machining time and simplify manufacturing processes.
HOW WE WORK
A clear scope before development.
- Understand requirements and available information
- Review technical constraints and feasibility
- Agree the scope and deliverables
- Develop the design or analysis
- Review results and next steps
POSSIBLE DELIVERABLES
Useful outputs for your next step.
3D CAD models · Manufacturing drawings · Design review reports · Engineering analysis reports · Manufacturing improvement recommendations
Project scope, deliverables, and manufacturing partner coordination are agreed for each project.
02 / EXPERIENCE & PHILOSOPHY
Experience that sees
the whole system.
Led by INHWAN CHANG, with hands-on experience in machining and manufacturing since 1994, followed by mechanical design and development across special-purpose machinery, precision cutting tools, jigs, fixtures, and production equipment.
Work begins with examining the required functions and constraints, with manufacturing and operating conditions considered throughout design development.
INHWAN CHANG — LinkedIn profile ↗
Discuss your engineering challenge ↗ENGINEERING PHILOSOPHY
Face the problem.
Find a way to solve it.
When a problem arises, I start with what I can solve. I learn what I do not know, check what needs to be understood, and expand the scope of what I can resolve. The answers are carried through design, manufacturing, and validation into practical solutions.
That process has led me across machines, products, cutting tools, and manufacturing processes. The experience gained by working through each problem has shaped the engineering I practice today.
EXPERIENCE & DESIGN METHOD
Engineering grounded in design
and manufacturing experience.
WHAT HALO MEANS
HALO
Hyper-Accurate Lifecycle Optimization
HALO connects requirements and concepts with design, analysis, manufacturing, validation, operation, and improvement. Results from each stage inform the next engineering decision, approaching an optimum with precision, performance, and service life considered together.
CHEONJI INNOVATION’s engineering brand, BHA Engineering, applies HALO Technology to the development and improvement of machines, products, and tools.
The performance of machines and tools depends on materials, stiffness, vibration, tolerances, machining, and assembly conditions as well as geometry. Design development considers these factors and the required performance to identify configurations suited to manufacture and operation.
HALO Technology is a design method that approaches an optimum through repeated cycles of design, analysis, manufacturing, and validation.
Experience gained in design and manufacturing informs the interpretation of analysis results and the incorporation of manufacturability and operating conditions into the design.
SELECTED DEVELOPMENT & RESEARCH
Requirements and ideas,
from concept to physical products.
Selected projects from Inhwan Chang’s engineering experience, with design records and development imagery.
01 / DEVELOPMENT FIELD
Precision Tooling & Surface Finishing
Hairline finishing products, special-tool design, and ultra-precision tool development.
01 / SPECIAL TOOL DEVELOPMENTSealing-surface hairline generationMechanical self-alignment and machining-center processing ↗02 / PRECISION CUTTING TOOLHybrid-body fine boring toolStructural dynamics, balance, and machining precision ↗03 / DESIGN RESEARCHSPDT cutting-tool researchGeometry and dynamic-response evaluation ↗
02 / DEVELOPMENT FIELD
Inspection Equipment & Workholding
Inspection access, workpiece location, and hydraulic fixture design.
03 / DEVELOPMENT FIELD
Production Equipment & Industrial Machinery
Dedicated equipment, production-line development, and manufacturing-process improvement.
04 / DEVELOPMENT FIELD
Mechanical Components & Functional Products
Requirements translated into mechanisms and manufacturable products.
05 / DEVELOPMENT FIELD
Mobility & Power Transmission
Integrated mechanical development across drive and braking systems.
01 / DEVELOPMENT FIELD
Precision Tooling & Surface Finishing
Hairline finishing products, special-tool design, and ultra-precision tool development.
01 / DEVELOPMENT CASE
Self-aligning hairline generation tool for sealing surfaces
LUX-TRACK mechanically follows the tool path to generate directional hairline patterns on O-ring contact surfaces.
WHY THE SEALING-SURFACE PATTERN MATTERS
Surface texture can create a leakage path.
Milling and grinding leave directional machining marks. Where grooves cross the seal contact band, they can leave channels across the interface and provide a potential leakage path.
The finishing approach removes the original machining pattern, then generates a fine directional pattern along the length of the seal path. LUX-TRACK mechanically follows that path, maintaining the finishing direction through straight sections and rounded corners.
Directional grooves remain after milling or grinding.
Grooves crossing the seal contact band can provide a path across the interface.
After removing the original machining pattern, a new fine directional texture is generated.
The finishing pattern follows the seal’s lengthwise direction to help limit cross-seal leakage paths.
Conceptual illustrations from the original development presentation. Sealing performance also depends on seal material, compression, surface specifications, and operating conditions.
The challenge
Manual finishing required shape-specific masking guides, prolonged hand work, and at least two complementary guides. The bridges holding each guide together covered part of the finishing path, so the operator had to exchange guides to finish the remaining sections.
The engineering approach
A mechanically self-aligning head follows straight paths and rounded corners while the machine spindle remains stationary. No programmable spindle-angle control is required. The head geometry also provides access to the bottom of dovetail O-ring grooves.
The application is defined by the sealing surface, rather than a single industry. Examples include semiconductor and display equipment chambers, vacuum chambers, and pressure chambers, on flat O-ring contact surfaces or dovetail groove bottoms.
Scope and outcome
Concept development, mechanical design, prototype manufacture coordination, and testing. Field trials demonstrated machining-center hairline generation and direction following through rounded corners. LUX-SAND provides an optional surface preparation stage.
Product purchase, technology transfer, and business enquiries are welcome ↗
Korean patent No. 10-2435651 · Registered August 19, 2022
Co-inventors: Inhwan Chang and Keunsoo Kim
View patent document ↗
Watch the field demonstration on YouTube ↗
Back to selected work ↑02 / DEVELOPMENT CASE
Hybrid-body guide-pad fine boring tool
Material selection, structural dynamics, and balance considered together for precision boring.
The challenge
The existing tungsten heavy-alloy body offered damping, but deformation and unbalance remained concerns. Guide-pad support alone did not address the full behavior of the rotating tool.
The engineering approach
Designed a hybrid body combining dissimilar materials to adjust stiffness, mass distribution, and natural frequencies. Compared structural configurations through analysis and incorporated unbalance correction into the design and manufacturing drawings.
Scope and result
Tool-body design, material and structural comparison, static and modal analysis, balance evaluation, and manufacturing drawings.
- Required coaxiality and roundness
- 7 μm each
- Reported machining result
- Approximately 2–3 μm each
The machining results were reported to the engineer following manufacture.
Development, design, engineering analysis, and technology transfer are available ↗
03 / RESEARCH STUDY
SPDT cutting-tool design research
Geometry development and structural dynamics evaluation for ultra-precision optical machining.
Research application
This study concerns diamond cutting tools for ultra-precision optical machining. The work covers tool geometry and clamping-structure design, supported by static, modal, and harmonic-response analysis.
Frequency-response evaluation
Harmonic analysis examines displacement and stress response as the excitation frequency changes. The response curves identify regions of increased response near resonance and support the evaluation of the tool structure.
The figures below show displacement response at Nodes 1 and 39, von Mises stress response at Nodes 1, 39, and 71, and a resultant-displacement distribution at 125,000 Hz (7,500,000 CPM). The 125,000 Hz (7,500,000 CPM) distribution is shown as a selected frequency result, rather than identified as the peak-resonance condition.
HALO TECHNOLOGY INSIDEHALO determines the
HALO determines the
SWEET SPOT.
Designed for high stiffness and superior resistance to chatter, the tool is evaluated at the overhang distance determined through the HALO sweet-spot process. The specific distance is not disclosed.
Running a harmonic analysis is one step. The demanding work is deciding which geometry, material combination, clamping structure, and overhang can deliver the intended response under the target machining conditions.
HALO Technology connects the disciplines shown around the HALO circle: idea, knowledge, design, analysis, design optimization, DFM, process design, process optimization, and validation. Redesign and repeated evaluation bring these decisions together to identify the sweet spot.
The HALO advantage is turning analysis into design decisions—determining the structure and conditions that work together toward the target performance.
This research presents the design and analysis stages; chatter resistance is a design objective, not a reported machining-test result.
COLLABORATION & DEVELOPMENTUltra-precision diamond tools.
Back to selected work ↑Ultra-precision diamond tools.
Developed through complementary expertise.
Joint development and commissioned engineering for ultra-precision diamond tools and holders, including SPDT. We work with diamond-tool manufacturers and precision-machining companies on new tools and improvements to existing products.
Design, analysis & optimization
HALO Technology connects tool geometry, body, holder, and clamping-structure design with static, modal, and harmonic-response analysis. We identify structures and operating conditions suited to the target application, and provide manufacturing drawings and application-specific requirements for edge geometry, controlled waviness, and chipping.
Diamond-edge manufacturing & inspection
Manufacturing partners implement the design through their expertise in crystal-orientation control, lapping, polishing, and edge preparation. They verify the agreed cutting-edge quality through inspection results, while retaining their proprietary manufacturing processes.
Manufacturability and performance requirements are reviewed together from the design stage. Prototype inspection and machining evaluations inform further design improvements. Development scope, responsibilities, and evaluation conditions are agreed for each project.
| Application Field | Example Workpieces / Features |
|---|---|
| Luxury — Watches & Jewelry | Watch dials, jewelry engraving details, decorative finishing surfaces |
| Imaging Optics | Camera-lens mold inserts and aspheric imaging-lens surfaces |
| Ophthalmic & Vision Care | Contact-lens forming molds and ophthalmic-lens profiles |
| Electronics — Microstructured Molds | Microgroove and micro-pattern mold inserts for electronic components |
| Aerospace — Reflective Optics | Precision reflective surfaces on aluminum mirrors |
Examples indicate potential tool-development applications. Suitability is reviewed for the specific material, geometry, equipment, and required finish. Enquiries for other workpieces are also welcome.
We engineer better.
From current results to better performance.
Discuss joint development or a new project ↗02 / DEVELOPMENT FIELD
Inspection Equipment & Workholding
Inspection access, workpiece location, and hydraulic fixture design.
04 / DEVELOPMENT CASE
Automatic endoscope inspection and hydraulic fixtures
Equipment development addressing inspection and workholding requirements on the manufacturing floor.
Automatic endoscope inspection
An automatic endoscope inspection system for examining internal features. The portfolio includes equipment photographs and an example inspection image.
Hydraulic jigs and fixtures
Hydraulic fixtures address workpiece location and clamping during machining. The inspection system and workholding fixtures are presented as separate applications within production engineering.
03 / DEVELOPMENT FIELD
Production Equipment & Industrial Machinery
Dedicated equipment, production-line development, and manufacturing-process improvement.
05 / DEVELOPMENT CASE
Deck production line and dedicated machinery
Developing a production line around the product and its manufacturing sequence.
Process and equipment planning
Reviewed how the product should be manufactured, established the process and production layout, and designed the machinery required for each operation. Equipment interfaces, material transfer, and the flow of work were considered as part of the line.
Scope and development records
Equipment design, fabrication, quality control, production layout planning, and documentation. CAD assemblies, line layout drawings, and photographs document the equipment and its operation. The dedicated machinery includes a weld joint preparation milling machine.
06 / DEVELOPMENT CASE
Large-format hybrid plate-cutting machine
Design and structural analysis for equipment handling steel plate up to 6,000 mm wide.
Machine configuration
The equipment combines oxygen, plasma, and laser cutting heads with a punching marker. The design considers the processing functions together with the supporting machine structure.
Structural evaluation
Structural analysis records examine load response, stress, and deformation in the large machine structure and its components. The images show the evaluated configurations and modeled load cases.
04 / DEVELOPMENT FIELD
Mechanical Components & Functional Products
Requirements translated into mechanisms and manufacturable products.
07 / DEVELOPMENT CASE
SMA-actuated fuel recirculation unit
A mechanical product developed around the fuel recirculation requirements of a diesel engine.
Product and operating principle
Developed a thermo unit using shape memory alloy (SMA) actuation to implement temperature-responsive operation within a fuel recirculation valve arrangement.
Design records
External and sectional CAD views illustrate the product design. The section shows the internal mechanism and its integration into the valve body.
05 / DEVELOPMENT FIELD
Mobility & Power Transmission
Integrated mechanical development across drive and braking systems.
08 / DEVELOPMENT CASE
Hubless electric bicycle system development
Mechanical integration of hydraulic power transmission, braking, and bidirectional freewheeling.
View project detailsHide project details
The challenge
The offset gear drive examined for this project required the drive shaft to rotate approximately four to five times faster than the wheel. Matching a conventional e-bike motor to the target wheel speed created a torque trade-off. Brake packaging and freewheeling were additional integration challenges.
The engineering approach
Developed a hydraulic power transmission arrangement to address the speed and torque requirements. Integrated hydraulic braking into the hubless wheel architecture and combined hydraulic and mechanical mechanisms to provide forward and backward freewheeling.
Scope and development evidence
Concept development, mechanical design, finite element analysis (FEA), manufacturing process planning, CNC programming, and production preparation. The photographs document the physical build, supported by CAD, CAM, and structural analysis records.
03 / START A CONVERSATION
Engineering projects & collaboration
Project enquiries and technical collaboration are welcome, from development, design, and analysis to manufacturing process planning and technology transfer.
Joint development and design or manufacturing engineering collaboration with diamond and precision cutting-tool manufacturers are also welcome.
Consultation can begin with a concept, sketch, existing drawing, photograph, or an improvement requirement. The project scope and deliverables are agreed according to its current stage.
Click the email address to copy.
04 / ENGINEERING INSIGHTS
Engineering ideas, everyday questions,
and perspectives from hands-on experience.