How To Evaluate Workstation Utilization
Summary
This article explains four methods for evaluating workstation utilization for the purpose of closely estimating the savings achievable with on-demand Ecogate systems.
What is Workstation Utilization?
Active Workstation Utilization, as we define it, doesn't necessarily account for the entire duration a worker spends at a workstation. Instead, it only factors in the time when the machine is actively producing particles for extraction. This excludes periods of loading/unloading materials, programming CNC, cleaning, maintenance, etc.
Ecogate control units (greenBOX Nxt & greenBOX Master) send data to our cloud servers every 10 seconds. This data assists in sending daily and monthly emails to maintenance personnel and management, respectively. Workstation active utilization is an integral part of this data.
Evaluating Workstation Active Utilization
Before installing an Ecogate system, it's crucial to assess the workstation active utilization. This helps in calculating the potential savings. Here are four options to do so:
Option 1
Some factories use a system that measures and records the number of products (parts or operations) a particular workstation produces per shift day and per month. This data helps determine each workstation's maximal capacity (recorded in percentage). Divide the actual production number by the maximal capacity to get a good average working utilization for the workstation.
Option 2
If the first option isn't available, you can measure utilization by observing the full production cycle with a stopwatch. The average utilization will be the cutting cycle time divided by the complete cycle time (recorded in percentage).
Option 3
If the first two options are not viable, then we can resort to a simple snapshot method to measure the utilization of the entire factory. Start with a full list of workstations and walk from machine to machine to record which ones are cutting material and which are not. After this, you calculate the percentage of active workstations. This method is not the most accurate because it is based on a snapshot. Surprisingly, however, it is pretty close to carefully measured numbers. You can conduct snapshots several times per shift(s) to improve the overall accuracy.
Option 4
For the most accurate utilization numbers, install sensors (data loggers) on motors driving the workstations' cutting tools. This is covered in more detail in the following sections.
Using Onset Data Loggers
As we mentioned earlier, the time when the machine is producing (therefore needing dust/mist/fume collection) is what needs to be recorded in our measurements. To do this we need data loggers that will record the time/date of when the motor of the cutting tool is active and the time/date of when it is inactive.
Note: Data loggers should only be placed on motors that are driving cutting tools, otherwise you will have incorrect data. For example, if you add a data logger to the vacuum pump of a CNC machine, that pump may be running the entire shift, which does not represent the active utilization of this CNC machine.
Simplified Step by Step Instructions
Here's a condensed list of steps that covers how to properly add data logger sensors to your workstations. Below this list, we go into more detail and include pictures!
Mount the data logger sensors on the cutting tool's motors and secure them properly (must withstand all vibrations for 2 weeks).
Start the cutting motor of the workstation.
Press the right 'Calibrate' button and hold it until the calibration sequence starts.
Test the sensor by starting and stopping the cutting motor. The sensor's LCD screen should indicate the proper status.
If the motor sensing is working correctly, deploy the sensor by pushing the 'Start' button and hold until the sensor begins logging (it will show 100% if the motor keeps running, and it will drop as the motor stops).
Leave the sensors installed for a minimum of two weeks.
After two weeks, use the 'Stop' button and hold to stop data logging. Collect all the sensors.
Onset HOBO UX90 Motor On/Off Data Loggers
We are using the new and improved generation of Onset HOBO UX90 Motor On/Off data loggers. These data loggers are not connected to the motor, instead, they are powered by a battery and can sense the magnetic field of an active motor. They can be attached to the motor using magnets and/or cable ties can be used to secure it further.
The magnetic field of the motor is sensed by two little coils, and the sensitivity can be properly adjusted by using the Calibration button. A nice LCD display will help you understand if the calibration was successful. To start logging simply press the Start button.
Collect data for at least two weeks. After this period, press the Stop button to stop collecting data and collect all sensors. Use a Micro USB cable to download the data onto a computer and use the HOBOWare software to evaluate the average utilization.
Since we are only interested in the utilization during the shift time, we can use the HOBOware software filter to display motor utilization:
The final result of the evaluation could be a table where we can see workstation active utilization day by day and weekday averages:
Before you deploy the sensor, you need to prepare it by using the HOBOware Launch option. Recommended settings are:
Internal (sensor): “State”
State Description: "Motor Off/Motor On"
LCD: For State and Runtime sensors, show: "%"
Start Logging: "Push Button"
Stop Logging: "When Memory Fills"
Check the "Push Button" box
Click “Button Start”.
Author, Ales Litomisky
