Can't Justify Full Automation? Semi-Automate With Paced Assembly and Robotic Work Cells

The rule of thumb for manufacturers today is that annual sales volume must exceed 1 million before a given product can be cost justified for full automation. The initial investment and payback periods are high when total automation is the goal.

Semi-automation is a cost-effective alternative. The equipment ingredients of such a system are:

  • Synchronous platform conveyor

  • Vibratory part feed system

  • Robotics

Semi-automation addresses a segment of a given product for automation and creates special work cells to accomplish same. It combines the disciplines of materials handling, product mechanization and direct labor control systems. Labor gains of 75% are possible using this method of assembly.

The typical consulting activity sequence necessary to convert products from a bench method of assembly to a semi-automated system is:

  • Phase OneIndexing Paced Conveyor System

    • Work measurement

    • Line balance

    • Final equipment specifications

    • Work station layout

    • Training

    • Paced system installation

  • Phase TwoSemi-Automated Work Cells

    • Design and fabrication

    • Programming

    • Electrical and mechanical installation

The time-balanced Phase One system prepares for Phase Two semi-automation by eliminating future time bottlenecks for operations not to be mechanized. Phase One gains include:


Improvement Comparison


From Bench or
Progressive Line

To Paced Assembly Line

Labor Gain






5% - 10%

  • Excessive moves/storages

  • Assembly where transported


  • Minor operations separate

  • Coordinated work flow


  • Work area scattered

  • Space saving by consolidation







5% - 10%

  • Tooling inadequate

  • Tooling specialized


  • Balanced by sequence

  • Balance controlled


  • Long work span

  • Short station times


  • Inefficient work place

  • Optimum work place


  • Quality separated

  • Quality integrated







15% - 20%

  • High responsibility

  • Lower responsibility


  • Output pegged to slowest

  • Efficiency level created


  • Measurement late

  • Measurement immediate


  • Long training period

  • Reduced learning curve


  • Poor work habits

  • Controlled work atmosphere





Total Average Improvement


25% - 40%

Phase Two gains in product mechanization leads to additional savings. They include:


From Bench or
Progressive Line

To Semi-Automated Cells

Labor Gains




Work Cell Sub Assembly



  • Manual part placement
    into container

  • Bulk hopper part feed


  • Manual removal of part
    from container and alignment
    into fixture

  • Precision vibratory bowl
    part positioning into fixture


  • Manual pneumatic/electric
    part fastening

  • Robotic part fastening





Work Cell S/A to
Paced Assembly F/A
Line Handling:



  • No precision platform

  • Precision in-line paced
    conveyor platform positioning


  • Manual placement of sub
    assembly to final assembly

  • Robotic pick from S/A work
    cell and place on fixturized
    paced conveyor F/A platform





Total Average Improvement


30% - 35%




The initial investment in the semi-automation technique is modest and a first-year return-on-investment guaranteed.


This article is provided by JD Gray Associates,  manufacturing productivity consultants specializing in materials handling, product automation and direct labor control systems. Industrial Engineering is the essence of the 25 year old company. For more information, please visit