November 10, 2017

Once or twice a month, we like to share IAI Actuator News with the automation community.
Here is a new Easy Automation Application Improvement video Vol.8-2.

Easy Automation Improvement Example Vol.8-2

Transfer System for Shaft Parts between Processes

34% reduction in system operating hours through optimization of
operating conditions and elimination of "choko-tei" (short disruption in production line)

 

System Overview

This is a reduction gear manufacturing line. The cutting process cuts shaft parts to a specified length, orients them vertically, then transfers them to the next shaft-end machining process.
Air cylinders are used to turn and transfer the shaft materials.

 

Problems when Air Cylinders are used

Ways to shorten cycle time and boost productivity are being looked at. However, raising the speed increases the stopping impact of the air cylinder and the occurrences of choko-tei, so reducing the cycle time wasn't feasible.
Shaft parts falling from abrupt stopping impacts are causing the choko-tei.

There are around 15 incidents of choko-tei per day. It takes 3 minutes for the system to recover from each choko-tei incident, meaning that around 45 minutes each day are being wasted.

 

Improvements Achieved by the ROBO Cylinder®

1. Shorter cycle time and zero choko-tei through speed, acceleration, and deceleration setting functions

The ROBO Cylinder lets you set desired speeds, accelerations and decelerations.

By setting the speed and acceleration high and the deceleration gradual, high-speed operation free from stopping shock became possible.

1.5 seconds of travel time was reduced on the Y-axis. Also, the impact-free operation eliminated choko-tei and recovery time.

  Relation of Y-axis operating time and speed  

 

Y-axis travel time

Air cylinder:
3.0 seconds

ROBO Cylinder:
1.5 seconds

Choko-tei recovery time a day

(3 minutes/incident)

Air cylinder:
45 minutes (15 incidents)

ROBO Cylinder:
0 minutes

 
 
2. Further cycle time reduction by adopting the shortest route

While gripping the shaft part, the Y-axis waits until the Z-axis reaches its highest position before moving to avoid interference. After releasing the shaft part and starting the return movement, however, raising the Z-axis to its highest position is no longer necessary since the Y-axis travel path is clear.

By setting the lowest possible position for the Z-axis cylinder during the return operation, another 0.8 seconds was reduced from the cycle time.

 

Cycle time

Air cylinder:
8.7 seconds

ROBO Cylinder:
7.2 seconds - 0.8 seconds = 6.4 seconds

 
 
3. If the system needs to operate for 10 years, it would require 12 air cylinder replacements. ROBO Cylinder replacements will not be needed.

Air cylinders lose speed (thrust force) after around 2 million operations due to deterioration of the gaskets, etc. The Y-axis and Z-axis air cylinders had to be replaced once every 1.5 years.

ROBO Cylinders can ensure stable operation even after many hours of use. When calculated under the current use conditions, the ROBO Cylinder has a service life of 15 million operations or more. The service life of ROBO Cylinders is equivalent to 10 years or longer.
 

Number of replacement units

Air cylinder:
12 units

ROBO Cylinder:
0 units

 

Cost Cutting Effect

(1) Conditions

Required production quantity 4,800 parts
Labor cost $18*/hour
Annual operating days 250 days

 
(2) Comparison of Air Cylinder and ROBO Cylinder®

Item System using air cylinder System using ROBO Cylinder
Modification cost - Total cost: $6,700*
Cycle time 8.7 seconds 6.4 seconds
Line operating hours 12.4 hours/day
Cycle time 8.7 seconds x 4,800 parts +
Choko-tei recovery time 0.75 hours =
Approx. 12.4 hours
8.5 hours/day
Cycle time 6.4 seconds x 4,800 parts
= Approx. 8.5 hours
Labor cost $55,800*/year
12.4 hours/day x $18*/hour x
250 days/year = $55,800*
$38.250*/year
8.5 hours/day x $18*/hour x
250 days/year = $38,250*
Purchase cost of replacement cylinders (estimate over 10 years) $6,900*/year
YZ unit air cylinders $1,150* x
6 replacements (replaced regularly
once every 1.5 years) = $6,900*
$0

 
(3) Cost Cutting Effect

Air cylinder ROBO Cylinder
Labor Cost (annual) $55,800* - $38,250* = $17,550*
Difference = $17,550*
Purchase cost of replacement cylinders (annual) $690* -
(Air cylinder $6,900*/10years)
$0 = $690*
Difference = $690*

 

Result

By adopting the ROBO Cylinder, it reduced cycle time by 34%,
eliminated choko-tei, and achieved $17,550* in annual savings.
Also, the ROBO Cylinder doesn't need replacing for at least 10 years.
It will help save another $690* in air cylinder replacement costs every year.

* Exchange Rate: 1(USD) = 100(Japanese Yen)

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