1. Definition of Assembly

Assembly is the process of combining individual parts, modules, drive components, sensors, wiring, and piping according to defined references and procedures in order to create a complete machine system with the required structure, motion, accuracy, function, and safety.

Assembly is not simply the task of connecting parts or tightening bolts.

The following relationships are physically realized through assembly:

• Positional relationships between parts

• Alignment of shafts and guides

• Fits between bearings and shafts

• Load transmission through drive systems

• Power transmission between motors and mechanisms

• Relationship between sensors and actual detection targets

• Connection between wiring and program I/O

• Relationship between pneumatic or hydraulic devices and operating direction

• Relationship between safety devices and hazardous areas

• Access and replacement structures for maintenance

The essence of Assembly is therefore:

To reproduce the functional relationships defined in design drawings as an actual machine structure.

2. Position within Machine Product Development

The product-development flow of general machinery can be expressed as follows:

Requirements → Design → Manufacturing → Assembly → Control Integration → Commissioning → Verification → Delivery

The role of each area is as follows:

Manufacturing creates the shape and quality of individual parts.

Assembly creates the relationships among those parts and completes them as one functional system.

3. Purpose of Assembly

The purpose of assembly is not simply to produce a completed machine shape.

The following results must be achieved simultaneously.

3.1 Structural Completion

• Frames and modules must be connected securely.

• The structure must support operating loads.

• Fastened joints must not loosen or deform during operation.

3.2 Realization of Motion Functions

• Axes must move in the required directions.

• Guides and drive systems must operate smoothly.

• There must be no interference or abnormal friction.

3.3 Realization of Accuracy

The following must remain within the required ranges:

• Position accuracy

• Parallelism

• Perpendicularity

• Concentricity

• Shaft alignment

• Repeatability

3.4 Support for Control Functions

• Sensors must accurately detect actual conditions.

• Motor direction must match the control direction.

• Home and limit positions must correspond to the control logic.

3.5 Maintainability

• Consumable and failed parts must be replaceable.

• Adjustment points must be accessible.

• Original performance must be restorable after reassembly.

4. Relationship Between Assembly and Design

Assembly quality is not determined only by the skill of the assembly worker.

A significant part of it is determined during the design stage.

A design that is difficult to assemble may cause the following problems:

• Part orientation is difficult to identify.

• The assembly sequence becomes complicated.

• Tool access is impossible.

• Datum surfaces are unclear.

• Sensor adjustment range is insufficient.

• Other parts cannot be installed after fastening.

• All surrounding parts must be removed for disassembly.

• The possibility of incorrect insertion is high.

• Assembly tolerances must be adjusted manually on site.

Assembly should therefore be treated as a product requirement from the design stage, not merely as a production-stage issue.

5. Difference Between Assembly and Manufacturing

Manufacturing

Manufacturing is the process of producing individual parts.

Main areas include:

• Machining

• Sheet-metal fabrication

• Welding

• Forming

• Heat treatment

• Surface treatment

• Parts purchasing

Assembly

Assembly is the process of combining manufactured parts and purchased components into a functional system.

Main areas include:

• Fastening

• Fitting

• Alignment

• Position adjustment

• Wiring

• Piping

• Lubrication

• Setting

• Inspection

Even when manufacturing quality is high, machine performance cannot be ensured if the assembly references are inaccurate.

Conversely, even highly skilled assembly work cannot achieve the required performance if the dimensional errors of the parts are excessive.

6. Difference Between Assembly and Commissioning

Assembly is the process of completing the physical machine structure.

Commissioning is the process of adjusting and verifying the completed machine so that it performs the required functions and achieves the required performance.

Items Confirmed during Assembly

• Are parts and modules installed correctly?

• Are fastening and alignment appropriate?

• Do wiring and piping match the drawings?

• Are sensors and actuators installed correctly?

• Is there any interference during manual movement?

Items Confirmed during Commissioning

• Are motor direction and speed appropriate?

• Does homing operate correctly?

• Does the sequence operate correctly?

• Do interlocks and protective functions operate?

• Are cycle-time and quality criteria satisfied?

It is not desirable to compensate for assembly defects using control parameters.

7. Basic Structure of Assembly

Assembly of general machinery generally consists of the following areas:

1. Structural Assembly

2. Precision Mechanical Assembly

3. Drive-System Assembly

4. Pneumatic and Hydraulic Assembly

5. Electrical and Control Assembly

6. Safety-System Assembly

7. Adjustment and Alignment

8. Inspection and Functional Verification

These areas are not independent and must be integrated according to a defined sequence and reference system.

8. Assembly Requirements

Assembly requirements should be defined before assembly work begins.

Structural Requirements

• Load support

• Rigidity

• Clamping force

• Vibration resistance

• Deformation limits

Accuracy Requirements

• Parallelism

• Perpendicularity

• Flatness

• Concentricity

• Position

• Shaft alignment

Functional Requirements

• Travel distance

• Operating direction

• Rotation direction

• Operating speed

• Home position

• Working position

Environmental Requirements

• Cleanliness

• Temperature

• Humidity

• Dust

• Washing

• Corrosion

Maintenance Requirements

• Access space

• Replacement time

• Adjustment method

• Disassembly sequence

• Reassembly criteria

9. Assembly Architecture

Rather than assembling the entire machine at once, it is generally more effective to divide it into functional modules and subassemblies.

Example Assembly Hierarchy

• Part

• Subassembly

• Functional Module

• Machine Module

• Complete Machine

• Production Line

Example:

Bearing + Shaft + Housing → Rotating-Shaft Assembly → Drive Module → Processing Module → Complete Machine

A clear assembly hierarchy simplifies:

• Outsourced assembly

• Module testing

• Defect isolation

• Transportation

• Field installation

• Option changes

• Maintenance

10. Boundaries of Assembly Modules

Each assembly module requires clearly defined boundaries.

Physical Boundary

• Mounting surface

• Datum surface

• Bolt positions

• Locating pins

• Power connection

• Piping connection

• Cable connection

Functional Boundary

• Module function

• Inputs and outputs

• Operating range

• Completion conditions

• Abnormal conditions

Inspection Boundary

• Items to verify at the module stage

• Items to verify on the complete machine

• Items requiring readjustment after assembly

Clear module boundaries allow functions and quality to be verified before the module is installed in the complete machine.

11. Datum and Reference

In precision assembly, it is important to define which surfaces and points are used to position components.

Types of References

• Primary datum surface

• Secondary datum surface

• Reference axis

• Reference hole

• Locating pin

• Assembly origin

A good reference structure has the following characteristics:

• It can repeatedly produce the same position.

• It can be measured.

• It can be easily identified by the assembly worker.

• It is located in a region with minimal deformation.

• Multiple parts share the same reference system.

If machining references and assembly references differ unnecessarily, tolerance accumulation may increase.

12. Constraint of Degrees of Freedom

To assemble a part accurately, the required degrees of freedom must be clearly constrained.

A part basically has six degrees of freedom:

• Translation along the X-axis

• Translation along the Y-axis

• Translation along the Z-axis

• Rotation about the X-axis

• Rotation about the Y-axis

• Rotation about the Z-axis

The designer should review which degrees of freedom are constrained by datum surfaces, pins, bolts, and guides.

Overconstraint may cause:

• The part cannot be assembled.

• Internal stress is generated.

• Thermal expansion cannot be accommodated.

• Guides or bearings become bound.

Insufficient constraint may cause poor positional repeatability and movement during operation.

13. Tolerance Stack-Up

When dimensional errors from multiple parts accumulate, the final assembly position may exceed the allowable range.

For example, the following may accumulate:

• Frame-hole position error

• Bracket-machining error

• Sensor-installation error

• Sensor repeatability error

As a result, the actual detection position may vary significantly.

Items Requiring Tolerance Stack-Up Review

• Center distance between axes

• Sensor position

• Motor and reducer alignment

• Guide parallelism

• Fixture position

• Product position

• Safety-device spacing

Countermeasures

• Use common datum surfaces.

• Apply adjustment structures.

• Use locating pins.

• Reduce the number of parts.

• Measure after assembly.

• Apply selective assembly.

• Use shims or spacers.

Adjustment structures can absorb manufacturing error, but they may increase assembly time and dependence on operator skill.

14. Assembly Sequence

The assembly sequence directly affects quality, workability, safety, and rework capability.

A good assembly sequence should:

• Begin with reference components.

• Install internal components before external covers.

• Perform alignment before final fastening.

• Perform intermediate inspections while measurement is still possible.

• Preserve space for wiring and piping.

• Install heavy parts in stable conditions.

• Keep adjustable parts accessible.

An incorrect assembly sequence may cause:

• Tools cannot reach the fastening point.

• Previously installed parts must be removed.

• Cables cannot be routed.

• Alignment references cannot be measured.

• Inspection and adjustment become impossible.

15. Assembly Direction and Accessibility

The direction from which parts are inserted and fastened must be considered.

Items to Review

• Part-insertion direction

• Bolt-tightening direction

• Tool-access direction

• Measuring-instrument access

• Cable-connection direction

• Piping-connection direction

• Disassembly direction

• Replacement-part removal direction

Where possible, assembly directions should be simplified and fastening directions standardized.

16. Fastening Design

Bolted fastening is the most common joining method in machine assembly.

However, a bolt does not merely attach parts. It generates the required clamping force.

Items to Review

• Bolt size

• Strength grade

• Fastening length

• Thread-engagement length

• Tightening torque

• Loosening prevention

• Washer use

• Repeated disassembly

• Corrosion

• Working space

Loosening-Prevention Methods

• Proper preload

• Spring washer

• Serrated washer

• Thread-locking compound

• Double nut

• Locknut

• Wire locking

• Mechanical locking structure

Excessive tightening may damage threads, deform components, and reduce accuracy.

17. Tightening-Torque Management

Tightening torque is an indirect method of controlling clamping force.

Items Requiring Torque Management

• Critical structural bolts

• Motor-mounting bolts

• Guide-mounting bolts

• Bearing housings

• Brakes

• Safety devices

• Pressure components

Management Methods

• Use of torque wrench

• Documentation of torque values

• Definition of tightening sequence

• Operator and tool management

• Completion marking

• Recording of critical fastening results

The tightening sequence is also important for components sensitive to deformation, such as plates and linear guides.

18. Distinction Between Positioning and Fastening

Bolts generally provide clamping force and do not always guarantee precise positioning.

Where repeatable positioning is required, the following may be used:

• Locating pins

• Precision pilots

• Keys

• Splines

• Reference shoulders

• Precision fits

Separating the positioning function from the fastening function improves reassembly repeatability after disassembly.

19. Fits and Press-Fitting

Shafts, bearings, bushings, and pins may be assembled using fits.

Purpose of Fits

• Position fixing

• Rotation prevention

• Load transmission

• Maintenance of precise centering

• Defined disassembly capability

Items to Review for Press-Fitting

• Interference

• Material strength

• Surface roughness

• Chamfer

• Press direction

• Press force

• Support position

• Deformation

• Removal method

When press-fitting a bearing, the assembly force must not be transmitted through the rolling elements.

20. Thermal and Cold Assembly

Parts with large interference may be assembled using temperature differences.

Examples:

• Bearing heating

• Shaft or bushing cooling

• Hot assembly of gears

Items to Review

• Heating temperature

• Cooling temperature

• Material thermal expansion

• Effect on lubricant

• Seal damage

• Working time

• Condensation and corrosion

• Position retention after assembly

Excessive heating may reduce the performance of the material or bearing.

21. Welded Assembly

Welding can provide high rigidity and an integrated structure, but it also causes thermal deformation.

Items to Review

• Welding sequence

• Symmetrical welding

• Jig restraint

• Heat input

• Deformation prediction

• Post-machining

• Stress relief

• Weld inspection

Precision-guide and bearing mounting surfaces are generally more stable when finish-machined after welding.

22. Adhesive and Other Joining Methods

In addition to bolting and welding, the following joining methods may be used:

• Adhesive bonding

• Riveting

• Snap fitting

• Caulking

• Crimping

• Clamping

Adhesive bonding is useful for stress distribution and joining dissimilar materials, but the following should be reviewed:

• Surface preparation

• Curing time

• Temperature and humidity

• Oil resistance

• Disassembly capability

• Quality inspection

23. Frame and Base Assembly

The frame and base establish the reference for the entire machine.

Items to Verify during Assembly

• Flatness of the installation surface

• Frame squareness

• Level

• Anchor positions

• Welding deformation

• Floor contact

• Leveling bolts

• Load distribution

If the frame reference is unstable, it becomes difficult to achieve the required accuracy for guides, axes, sensors, and tooling installed above it.

24. Leveling

A machine may require leveling to compensate for irregularities in the installation surface.

Leveling Targets

• Machine base

• Precision table

• Long linear guide

• Frame modules

• Production-line interfaces

Precautions

• Do not excessively deform the frame using leveling bolts.

• Check changes before and after anchor tightening.

• Recheck under operating load.

• Apply grouting or pads where necessary.

25. Linear-Guide Assembly

Linear-guide assembly directly affects linear-motion accuracy.

Basic Assembly Procedure

1. Clean the datum surface.

2. Remove burrs and contaminants.

3. Seat the reference rail against the reference shoulder.

4. Tighten in the specified sequence and to the specified torque.

5. Align the secondary rail using the moving table.

6. Check travel resistance and parallelism.

7. Confirm lubrication condition.

Precautions

• Do not force rail alignment using bolts.

• Remove dirt and burrs from datum surfaces.

• Prevent blocks from coming off the rail.

• Confirm block orientation and reference surfaces.

• Do not damage protective seals.

26. Ball-Screw Assembly

In ball-screw assembly, shaft alignment and bearing preload are important.

Main Components

• Ball screw

• Fixed-side bearing

• Support-side bearing

• Nut

• Nut housing

• Coupling

• Motor

Items to Review

• Distinction between fixed and support sides

• Axial play

• Bearing preload

• Parallelism between nut and guide

• Shaft bending

• Coupling alignment

• Lubrication

• Protective cover

If the ball screw and linear guide are not parallel, travel resistance and load will increase.

27. Bearing Assembly

Bearing assembly directly affects rotational accuracy and service life.

Items to Confirm

• Bearing type and orientation

• Shaft and housing fits

• Direction of press force

• Preload

• Axial retention

• Lubrication

• Seals

• Rotational resistance

• Noise

When pressing the bearing inner ring onto a shaft, force should be applied to the inner ring.

When pressing the outer ring into a housing, force should be applied to the outer ring.

28. Shaft and Coupling Assembly

When connecting a motor shaft and driven shaft using a coupling, alignment must be verified.

Items to Review

• Shaft-center offset

• Angular misalignment

• Axial distance

• Key position

• Set screws

• Tightening torque

• Coupling allowable misalignment

• Shaft-end gap

The fact that a coupling can absorb some misalignment does not justify excessive assembly error.

Excessive misalignment causes bearing load, vibration, heat generation, and reduced service life.

29. Belt and Chain Assembly

Belt Assembly

• Pulley alignment

• Belt tension

• Tooth engagement

• Tension-adjustment range

• Guard installation

Chain Assembly

• Sprocket alignment

• Chain tension

• Lubrication

• Connecting-link orientation

• Sag

• Guard installation

Excessive tension increases bearing load, while insufficient tension causes disengagement and vibration.

30. Gear and Reducer Assembly

Items to Review

• Gear engagement

• Backlash

• Contact pattern

• Shaft alignment

• Lubricating oil

• Oil seals

• Rotation direction

• Torque arm

• Breather position

If the mounting orientation of the reducer changes, the lubrication method and oil level may also change.

31. Pneumatic Assembly

Pneumatic assembly includes device installation and piping configuration.

Main Components

• Filter and regulator

• Valves

• Cylinders

• Vacuum devices

• Pressure sensors

• Flow controllers

• Tubes and fittings

Assembly Review Items

• Supply and exhaust directions

• Port numbers

• Normal valve state

• Tube bending radius

• Fitting tightening

• Leakage

• Exhaust routing

• Residual-pressure exhaust

• Tube identification

Incorrect piping connections may reverse the forward and reverse directions of the cylinder relative to the control definition.

32. Hydraulic Assembly

Because hydraulic systems use high pressure, cleanliness and leakage control are critical.

Items to Review

• Piping cleanliness

• Hose pressure rating

• Fitting tightening

• Supply and return connections

• Air removal

• Filters

• Oil level

• Leakage

• Pressure test

• Hose movement

Contamination inside piping may cause valve and cylinder failure.

33. Lubrication Assembly

Lubrication is not an auxiliary task performed after assembly. It directly affects equipment life.

Items to Review

• Lubricant type

• Initial lubrication quantity

• Lubrication point

• Automatic-lubrication piping

• Lubrication interval

• Contamination prevention

• Lubrication-state confirmation

The possibility of mixing incompatible lubricants should also be reviewed.

34. Seal and Gasket Assembly

Seals and gaskets prevent fluid leakage and contamination ingress.

Assembly Precautions

• Installation direction

• Damage to contact surfaces

• Twisting

• Lubrication

• Compression ratio

• Reuse

• Material compatibility

• Tightening sequence

Gasket fastening may be performed diagonally or in a specified sequence to ensure uniform compression.

35. Electrical Assembly

Electrical assembly is the process of electrically connecting control panels, sensors, motors, cables, and field devices.

Main Tasks

• Installation of panel components

• Terminal-block wiring

• Cable routing

• Sensor connection

• Motor and drive connection

• Grounding

• Communication-cable connection

• Cable labeling

Items to Confirm

• Consistency between electrical drawings and actual wiring

• Voltage and polarity

• PNP/NPN type

• Power capacity

• Grounding

• Shielding

• Cable separation

• Connector direction

• Terminal-tightening condition

36. Cable Routing

Cables must be routed considering machine motion and maintenance.

Items to Review

• Minimum bending radius

• Number of motion cycles

• Use of cable carriers

• Torsion

• Tension

• Friction

• High-temperature areas

• Sharp edges

• Detachable connectors

• Spare length

Power cables, encoder cables, analog cables, and communication cables should be separated considering noise effects.

37. Cable and Device Identification

All cables and devices require an identification system consistent with the drawings.

Identification Targets

• Sensors

• Motors

• Valves

• Terminals

• Cables

• Connectors

• I/O modules

• Network nodes

A clear identification system simplifies:

• Assembly

• Inspection

• Commissioning

• Fault diagnosis

• Component replacement

38. Sensor Assembly

Sensor installation directly affects the reliability of Control State Recognition.

Items to Review

• Detection target

• Sensing distance

• Installation direction

• Reference position

• Adjustment range

• Repeatability

• Bracket rigidity

• Contamination protection

• Collision protection

• Cable direction

If the sensor bracket is insufficiently rigid, vibration and impact may change the detection position.

39. Actuator Assembly

Pneumatic Cylinders

• Mounting-axis alignment

• Rod side load

• Stroke

• Cushioning

• Sensor position

• Piping direction

Electric Actuators

• Mounting surface

• Motor direction

• Home position

• Limits

• Cable movement

• Brake

• Load alignment

An actuator should not be used to forcibly compensate for mechanism misalignment.

40. Safety-Device Assembly

The position and installation condition of safety devices affect actual hazard-reduction performance.

Main Devices

• Safety doors

• Door switches

• Light curtains

• Emergency-stop buttons

• Protective covers

• Safety mats

• Safety scanners

• Mechanical stops

Items to Confirm

• Does the device sufficiently block the hazardous area?

• Is bypassing difficult?

• Is the operating distance appropriate?

• Can the device move due to impact?

• Are cables protected?

• Is maintenance access possible?

41. Assembly Jigs and Tools

Assembly jigs improve repeatability and workability.

Roles of Assembly Jigs

• Part positioning

• Temporary holding

• Alignment

• Press-fitting

• Welding-deformation control

• Provision of inspection references

Main Tools

• Torque wrench

• Press

• Bearing heater

• Dial indicator

• Laser alignment tool

• Precision level

• Height gauge

• Insulation-resistance tester

• Pressure tester

Jigs and tools also require calibration and condition management.

42. Cleanliness Control during Assembly

Contamination control is important in precision machinery and fluid systems.

Contamination-Sensitive Components

• Bearings

• Linear guides

• Ball screws

• Hydraulic valves

• Pneumatic valves

• Seals

• Optical sensors

• Connectors

Management Methods

• Cleaning before assembly

• Workbench cleaning

• Protective covers

• Minimization of open exposure time

• Glove use

• Cleaning-agent control

• Controlled air-blowing conditions

43. Part Protection during Assembly

Precision parts may be damaged by impact or contamination during assembly.

Protection Targets

• Machined datum surfaces

• Linear rails

• Ball screws

• Sensor lenses

• Connector pins

• Sealing surfaces

• Painted surfaces

• Safety devices

Temporary protective covers and transportation jigs may be applied.

44. Error Proofing

Assembly errors should not depend only on operator attention.

Error-Proofing Methods

• Asymmetrical shapes

• Different connectors for different orientations

• Pins and keys

• Color identification

• Part-number labels

• Barcode verification

• Fastening detection

• Automatic sensor checks

• Software-configuration verification

A good assembly design should make incorrect assembly difficult or make incorrect assembly immediately detectable.

45. Adjustment

After assembly, position, clearance, tension, or preload may need to be adjusted.

Main Adjustment Items

• Sensor position

• Belt and chain tension

• Guide parallelism

• Gear backlash

• Bearing preload

• Brake clearance

• Stopper position

• Product-guide width

• Clamping pressure

Each adjustment item should include:

• Adjustment range

• Target value

• Measurement method

• Locking method

• Readjustment condition

• Allowable tolerance

46. Shims and Spacers

Shims and spacers are used to compensate for assembly errors.

Application Examples

• Motor-height adjustment

• Guide parallelism

• Frame leveling

• Sensor position

• Fixture height

When using shims, the following should be managed:

• Material

• Thickness

• Number of layers

• Installation position

• Retention

• Assembly record

Excessive use of shims may indicate that part manufacturing or design references are inadequate.

47. Preload and Clearance

Preload or appropriate clearance may be required for machine rigidity and motion performance.

Components Requiring Preload

• Bearings

• Linear guides

• Ball screws

• Gears

• Couplings

• Clamps

Components Requiring Clearance

• Thermal-expansion areas

• Sliding areas

• Covers

• Guards

• Product guides

Excessive preload increases friction and heat, while insufficient preload increases play and vibration.

48. Assembly Inspection

Assembly inspection verifies more than whether all components have been installed.

Visual Inspection

• Missing parts

• Incorrect orientation

• Damage

• Contamination

• Labels

• Wiring and piping

Dimensional Inspection

• Position

• Height

• Gap

• Parallelism

• Perpendicularity

• Level

Fastening Inspection

• Torque

• Loosening prevention

• Completion marking

• Missing bolts

Functional Inspection

• Manual movement

• Rotational resistance

• Interference

• Leakage

• Sensor operation

• Brake operation

49. Intermediate Inspection

Items that cannot be checked after final assembly must be inspected during intermediate stages.

Examples:

• Internal frame wiring

• Bearing preload

• Seal condition

• Internal piping

• Guide datum surfaces

• Fastening inside covers

• Internal weld structures

The location and timing of intermediate inspections should be included in the assembly procedure.

50. Functional-Unit Testing

Subassemblies and functional modules can be tested independently before installation in the complete machine.

Test Examples

• No-load rotation of a rotating shaft

• Pneumatic-cylinder operation

• Valve leakage

• Sensor detection

• Motor and brake operation

• Electrical-panel power

• I/O modules

• Safety devices

Functional-unit testing reduces the range of defects encountered at the complete-machine stage.

51. Types of Assembly Defects

Position Defects

• Part-position error

• Sensor-position error

• Shaft misalignment

Fastening Defects

• Insufficient tightening torque

• Missing bolts

• Damaged threads

• Missing locking method

Motion Defects

• Excessive friction

• Interference

• Incorrect tension

• Bearing damage

Wiring and Piping Defects

• Incorrect wiring

• Polarity error

• Incorrect port connection

• Leakage

• Cable damage

Setting Defects

• Sensor sensitivity

• Pressure setting

• Brake clearance

• Limit position

52. Distinction Between Assembly Defects and Design Causes

Repeated assembly defects should not be treated only as operator error.

Possible design causes include:

• Tolerances are excessively tight.

• Datum surfaces are unclear.

• Tool accessibility is poor.

• Orientation is difficult to distinguish.

• Adjustment range is insufficient.

• Part rigidity is insufficient.

• The assembly sequence is inappropriate.

• Work instructions are unclear.

Repeated defects require review of both the assembly process and the design structure.

53. Design for Assembly

Design for Assembly is a design approach intended to make assembly easier and more accurate.

Main Principles

• Reduce the number of parts.

• Simplify assembly directions.

• Reduce confusion caused by left-right symmetry.

• Make directional parts easy to identify.

• Reduce the number of fastener types and tools.

• Apply self-locating structures.

• Provide tool-access space.

• Minimize adjustment work.

• Assemble and test by module.

• Consider disassembly and replacement.

54. Modular Assembly and Product Options

When product specifications vary, assembly modules may be configured as option units.

Examples:

• Standard feeding module

• Additional inspection module

• Additional servo axis

• Safety-door option

• Automatic-discharge option

• Cleaning module

Each option module should include:

• Mechanical parts

• Electrical parts

• Wiring and piping

• Software functions

• Assembly instructions

• Inspection criteria

55. Assembly and Maintainability

Maintenance can be considered a reverse assembly process.

Items to Review

• Can failed components be replaced without removing surrounding parts?

• Is there sufficient tool space?

• Can the component be lifted or removed?

• Can cables and piping be disconnected easily?

• Can the original reference position be restored after reassembly?

• Can adjustment values and parameters be restored?

56. Field Installation and Reassembly

Large machines may be disassembled into modules for transportation and reassembled at the customer site.

Required Items

• Module-connection references

• Locating structures

• Field leveling

• Cable and piping connections

• Removal of transportation fixtures

• Realignment criteria

• Field I/O verification

• Recommissioning procedure

Connections that are disassembled for transportation should be designed for repeatable reassembly accuracy.

57. Relationship with Control

Assembly creates the physical basis for control functions.

Main Relationships

• Motor direction and control command

• Sensor position and state recognition

• Home position and coordinate system

• Limits and software restrictions

• Brake and safety stop

• Valve direction and cylinder motion

• Wiring and I/O address

If assembly information does not match control information, the following problems may occur:

• An axis moves in the opposite direction.

• Sensor states are displayed in reverse.

• Home and limit positions are exchanged.

• Cylinder forward and reverse motions are reversed.

• The brake is controlled in the opposite manner.

58. Relationship with Manufacturing

Assembly connects the quality of manufactured parts to actual product performance.

Required Connection Information

• Part tolerances

• Datum surfaces

• Surface condition

• Assembly direction

• Fits

• Fastening conditions

• Inspection results

• Part traceability information

When a machined part changes, the effect on assembly references and assembly processes should be reviewed.

59. Relationship with Product Integration

During Assembly, mechanical, electrical, pneumatic, control, and safety systems are integrated into one product.

Therefore, assembly completion does not simply mean that all parts have been installed.

The following relationships must also be connected:

• Machine modules

• Electrical devices

• Piping

• Control signals

• Safety devices

• Product data

• Test documentation

• Version information

60. Assembly Documentation

Main Assembly Documents

• Assembly drawings

• Exploded views

• Assembly-sequence diagrams

• Parts lists

• Tightening-torque tables

• Wiring diagrams

• Piping diagrams

• Sensor-installation drawings

• Adjustment specifications

• Inspection sheets

• Module test sheets

• Field-installation procedures

Good assembly documentation should make it possible to reproduce the same quality without depending only on the experience of skilled workers.

61. Requirements for Assembly Drawings

Assembly drawings should include:

• Part positions

• Datum surfaces

• Assembly directions

• Fastening elements

• Locating elements

• Adjustment ranges

• Lubrication

• Seals

• Critical tolerances

• Cautions

• Part numbers

• Related subassembly drawings

The complete assembly intent cannot be communicated by model geometry alone.

62. Work Instructions

Work instructions define the assembly process and inspection methods step by step.

Required Contents

• Parts to prepare

• Tools to use

• Assembly sequence

• Fastening conditions

• Measurement methods

• Intermediate inspections

• Safety precautions

• Completion criteria

• Defect handling

Photographs and illustrations are effective for explaining complex assembly directions and wiring routes.

63. Assembly Traceability

Critical assembly information may need to be recorded.

Items to Record

• Operator

• Date and time

• Part serial numbers

• Tightening torque

• Measurement results

• Adjustment values

• Parts used

• Inspection results

• Rework

• Program and parameter versions

Traceability supports cause analysis and scope determination when quality problems occur.

64. Major Design Deliverables

65. Assembly Review Questions

Assembly Structure

• Is the machine divided into appropriate assembly modules?

• Are the reference components and assembly datums clear?

• Can each module be tested independently?

• Have transportation and field installation been considered?

Datums and Tolerances

• Are datum surfaces and datum axes clear?

• Are machining and assembly datums consistent?

• Has tolerance stack-up been reviewed?

• Is sufficient adjustment range available?

Assembly Sequence

• Is the assembly sequence clear?

• Are tools and measuring instruments accessible?

• Are intermediate inspection points defined?

• Does rework require excessive disassembly?

Fastening and Joining

• Are tightening torques defined?

• Is the loosening-prevention method appropriate?

• Are positioning and fastening functions separated?

• Are press-fitting and fit conditions defined?

Precision-Motion Components

• Is there a defined method for aligning guides and ball screws?

• Are bearing preload and clearance controlled?

• Is motor and driven-shaft alignment verified?

• Are travel resistance and interference inspected?

Wiring and Piping

• Does actual wiring match the electrical drawings?

• Are cables and tubes identified?

• Are bending radius and motion conditions appropriate?

• Are leakage and incorrect piping checked?

Sensors and Control

• Does the sensor position represent the actual state?

• Do home and limit positions match the control logic?

• Do motor and cylinder directions match the control definitions?

• Can I/O be checked after assembly?

Maintenance

• Can failed components be replaced easily?

• Can original position and performance be restored after replacement?

• Are adjustment and lubrication points accessible?

• Is service documentation available?

Quality and Traceability

• Are critical assembly values recorded?

• Are design causes reviewed for repeated defects?

• Are assembly tools and measuring instruments managed?

• Can assembly history be traced for each machine?

66. Conclusion

Assembly is not simply the task of combining individual parts and devices into a machine shape.

It is the process of realizing the designed structure, motion, accuracy, control, safety, and maintenance relationships as an actual product.

The key is to establish the following relationships consistently:

• Parts and datum surfaces

• Positioning and fastening

• Tolerances and final accuracy

• Guides and drive systems

• Motors and actual motion direction

• Sensors and actual machine states

• Wiring and program I/O

• Piping and actuator motion

• Safety devices and hazardous areas

• Assembly procedures and inspection criteria

• Assembly results and product performance

Proper Assembly does not depend only on the judgment of skilled workers.

It clearly defines datum surfaces, tolerances, assembly sequence, fastening conditions, alignment methods, inspection criteria, and traceability information so that the same functions and quality can be reproduced across multiple workers and multiple machines.

Assembly also connects Design, Manufacturing, Control Implementation, Commissioning, and Maintenance so that the machine can maintain the required structure and performance not only during initial production, but also after transportation, installation, long-term operation, component replacement, and modification.