Case Study 2: Application of an Engineering Control in the Retail Apparel Industry

An Italian retail apparel company stocks and supplies sport clothes, shoes and fitness accessories for an Italian athletic apparel franchise. Manual workers prepare the orders for customers by picking the products from the warehouse and placing them into plastic carts. Carts are about 70 cm tall. After completing the order picking, workers empty the full cart in a hopper (Figure 1). The hopper feeds a conveyor system with a sorter for the automatic sorting of clothes, shoes and accessories. The speed of the conveyor is 2 m/s, while the sorter sorts about 10,000 items per hour.

Manual order picking is performed several times per shift. The risk assessment revealed the presence of biomechanical overload of back and upper limb due to manual emptying of the carts. Such activity involves repetitive movements of the upper limb and awkward postures of shoulders, elbow, wrist and hand. Furthermore, workers assume a static position, maintaining a back flexion posture for several minutes while emptying the carts or handling loads over 3 kg (Figure 2).

Figure 1. Cart emptying in the sorting area.

Figure 2. Manual worker performing cart emptying.

Such work conditions suggest the adoption of an engineering control to improve the ergonomics of the analyzed task. The following is the implementation of the proposed procedure for the application of the engineering control.

Application of the Proposed Procedure

1. Problem Identification

Employer, occupational health specialist, external safety coordinator and workers representative perform the ergonomic analysis of cart emptying. Workers maintain the back flexion posture for more than the maximum time allowed (one minute) while emptying the carts (ISO 11226). The simplified ergonomic risk assessment from the ISO/TR 12295 has revealed high risk for the upper limb and back. In particular, the high-risk condition is due to the static back flexion posture, rather than the manual handling of the items.

2. Nominee of the TC

Employer, production manager and external safety coordinator nominate the TC. The following employees compose the team: external safety coordinator, workers representative, external consultant expert on ergonomics, sorting area supervisor.

3. Reunion of the TC
3.1. Screening of the Alternatives and Choice of the Control

Given the evident disergonomics of cart emptying and the difficult interaction between the operator and the cart, the TC chooses to install the customized semi-automatic handling and lifting device in Figure 3.

 

Figure 3. Semi-automatic handling and lifting device in the sorting area.

The engineering control in Figure 20 lifts the containers to a predefined height, allowing the workers to empty the carts in upright posture with an acceptable arm position.

Consequently, the device eliminates the ergonomic risk for the back due to the static back flexion posture.

3.2. Plan of the Intervention

The TC contacts the supplier or the manufacturer of the solution to define the plan of the intervention. The design of the manipulator, the realization of the customized parts and the installation in the plant requires two months.

3.3. Definition of the Formation and Training Programs

The TC plans one or two training day for the personnel involved, based on the availability of the workers and the work shifts. The program of the training day includes a theory session of one hour, followed by a thirty-minutes practical session. The ninety workers performing cart emptying are involved in the program. The external safety coordinator delivers the formation program to the workers, while the workers representative and the sorting area manager are responsible for the training session. No post-training test is required to verify the knowledge and the abilities of the personnel involved.

4. Intervention and Adoption of the Solution

The intervention is performed as planned in Step 3.2. The semi-automatic handling and lifting device works at full speed following the pre-defined time schedule.

5. Actuation of the Formation and Training Programs

The ninety workers assigned to order picking tasks participate in the formation and training programs as planed in Step 3.3. The programs start the day after the installation of the device in the sorting area.

6. Check and Analysis of the Results

The supervisor of the sorting area monitors the proper utilization of the solution.

6.1. If the Check Is Ok, Then Perform a Task Analysis after 6/12 Months

The safety coordinator, the external consultant and the workers representative perform an initial check two months after the conclusion of the intervention. Further periodic checks are scheduled every 6 months. The occupational health specialist certifies the workers’ fitness to work every year, assessing the improvements in their safety and health.

6.1.1. Repeat Step 6.1 until check is not ok
6.2. If the check is not ok, go to Step 1

 

During the training program and after the installation of the solution, the personnel involved have noticed potential improvements of the device to enhance the biomechanical risk reduction. The features of the device do not allow the complete cart overturn, as the width of the cart is larger than the hopper of the sorter. In particular, the 180-degree turn of the cart causes the discharge of the items out of the hopper. Consequently, the utilization of the device is limited to lifting tasks. The device tilts the cart by 90 degrees and manual workers perform upper limb repetitive movements to empty the containers.

The check is not ok and the procedure restarts from Step 1.

1. Problem Identification

The external safety coordinator and the workers representative verify the impossibility to overturn and empty the cart into the hopper without dropping any items. The device lifts the cart allowing the operator to assume an upright posture while emptying the cart. Despite the ergonomic improvement for the back posture, repetitive movements of the upper limb are still present.

2. Nominee of the TC

The following employees compose the TC: external safety coordinator, workers representative, external consultant expert on ergonomics, sorting area supervisor.

3. Reunion of the TC

 

3.1. Screening of the Alternatives and Choice of the Control

The observation of the solution during its first application for cart emptying suggests making changes to the initial configuration of the device. The TC decides to apply two lateral barriers on the gripper of the semi-automatic lifting and handling device (Figure 4).

The barriers narrow the opening of the cart, preventing the items to fall outside the hopper during cart emptying. Consequently, the manual worker is not necessary to empty the cart and the ergonomic risk is deleted.

Figure 4. Semi-automatic lifting and handling device with lateral barriers.

3.2. Plan of the Intervention

The TC contacts the manufacturer of the solution to define the plan of the intervention. The design of the barriers, the realization of the customized parts and the installation on the semi-automatic lifting and handling device requires one week.

3.3. Definition of the Formation and Training Programs

The TC plans one or two training day for the personnel involved, based on the availability of the workers and the work shifts. The sorting area manager, delivers an additional 15-20 minutes training session to the personnel involved. The workers representative takes part in the training sessions.

4. Intervention and Adoption of the Solution

The intervention is performed as planned in Step 3.2. The modified semi-automatic handling and lifting device works at full speed following the pre-defined time schedule.

5. Actuation of the Formation and Training Programs

The workers assigned to manual order picking participate in the formation and training programs as planed in Step 3.3. The programs start the day after the installation of the device in the sorting area.

6. Check and Analysis of the Results

The intervention has deleted the manual task and cart emptying is automatic. Carts containing special items (e.g., shoes boxes) require the manual operator to realize the transfer to the hopper. In these cases, the device lifts and turns the cart while the manual operator empties the contents assuming an acceptable posture of back and arms. The application of the risk assessment methods in the ISO/TR 12295 reveals an acceptable risk for both the back and the upper limb. Finally, the supervisor of the blending area monitors the proper utilization of the solution, ensuring the respect of the directions in the practical guideline.

6.1. If the Check Is Ok, Then Perform a Task Analysis after 6/12 Months

The sorting area manager continuously verifies the proper utilization of the device during the work shifts. The safety coordinator, the external consultant and the workers representative perform an initial check two months after the conclusion of the intervention. Further periodic checks are scheduled every 6 months. The occupational health specialist certifies the workers’ fitness to work every year, assessing the improvements in their safety and health.

6.1.1. Repeat Step 6.1 until check is not ok
6.2. If the check is not ok, go to Step 1