Mechatronics Technology: Part Alignment Without a Parts Feeder

Introduction

In the assembly process, the alignment of small parts is a critical factor that directly impacts work efficiency and quality. Traditionally, parts feeders have been used to align and supply parts; however, their high implementation cost—ranging from 600,000 to 2 million yen per unit—often makes them impractical for small-lot production or prototyping. Against this backdrop, our Toyama Plant took on the challenge of “part alignment without using parts feeders” and succeeded in developing a highly efficient, in-house alignment device while keeping costs down. In this article, we will provide a detailed overview of the specific initiatives undertaken and the results achieved.

Background of the Challenge

The focus of this improvement effort was the assembly lines for smart meters and the assembly processes for insert-molded products. The conventional manual methods presented the following challenges:

• Small screws and nuts must be aligned in the correct orientation before being inserted into the jig, which is labor-intensive for operators.

  
  

  ・If a part is inserted in the wrong orientation, the jig must be removed and the process repeated, leading to variations in processing time.

  ・Implementing a parts feeder is costly and imposes constraints on the automation of the entire production line.

  ・To address these challenges, the production team decided to build their own “inexpensive, compact alignment device that can be easily integrated into the production process.”

  
  

  Development Process of the Alignment Device

  
  

  In developing the alignment device, the following specific innovations and processes were implemented.

  
  

  ① Concept and Target Values

  Concept: Improve productivity by optimizing the bottleneck process; manufacture a compact device that can be installed within the production line

  
  

  Targets: Reduce cycle time by 6 seconds; keep device manufacturing costs under 500,000 yen

  
  

  ② Design Innovations

  No vibration mechanism: Reduced costs by using gravity conveyance

  Support for two-handed operation: Installed two rails to allow operators to pick up screws with both hands simultaneously

  Improvements to the blow mechanism: Prevented jams by changing the direction of the air blow to the front

  Improvements to the Alignment Box: To prevent screws from getting caught, the angle of the bottom surface was matched to that of the rails

  
  

  As a result, we succeeded in significantly reducing costs and space requirements while maintaining the same alignment functionality as conventional parts feeders.

  
  

  Implementation Examples and Results

Fastener Feeder

A similar alignment device was applied to the feeding of M4 and M5 nuts used in insert molding. It was determined that a simple feeding capacity sufficient to handle a 50-second molding cycle would be adequate, and it was decided that a custom-built device could handle the task.

Results:

Compared to commercial part feeders (1 million yen × 2 units), the in-house devices cost 200,000 yen × 2 units + 100,000 yen for additional parts = 500,000 yen.

This resulted in a reduction of 1.5 million yen in equipment manufacturing costs.

Issues and Countermeasures

Although several issues arose during the development process, they were resolved through ingenuity on the shop floor.

Ploblem	Measures
Screws get jammed in the alignment rail	Change the air blow direction to the front
There are too many screws, so it won't fly.	Install guides on the alignment rails to maintain a consistent volume.
The corner of the screw gets caught	Smoothly adjust the angle of the bottom of the box to match the rails
The screw at the back falls out	A cover is installed at the rear to prevent it from lifting up.

Furthermore, to address the issue of jams caused by excessive feed rates into the hopper, we plan to introduce a “fixed-volume feed cylinder” to automate the process.

Integration with Automation and Future Prospects

The developed alignment device is also being utilized as a component of automated machinery, and on the smart meter production line, alignment and conveyance are integrated as follows:

Alignment and Feeding: Nuts and screws are aligned using gravity.

Conveyance: Taking advantage of the vertical alignment, parts are conveyed using a simple structure.

Insertion Mechanism: An insertion chuck transports the parts to the mold and positions them accurately.

This method eliminates the need for a parts feeder, significantly reducing the total cost of the automated machine.