Case Study: How Roar Simulation Improves Distribution Center Operations

Conveyor merge and sorter Conveyor merge and sorter

Let’s face it — our impatient world has created the demand for fast-paced fulfillment, from everything from binge-watched TV to next day shipping on millions of retail items. For most Fortune 100 retailers, efficiency is not a question of desire, but rather it is the way a company holds an edge on its competition. Even for big companies, however, adapting old designs to new realities and pressures can be difficult to implement.

That’s where the power of simulation comes in—as companies can test and revise their operational equipment’s settings to better accommodate ongoing efficiency needs as well as peak seasonal demands.

Roar Simulation worked with a well-known household name Fortune 100 retailer (referred to below as The Company) to improve their distribution centers throughout North America using a flexible and configurable conveyor model customized through AutoMod’s analysis tool AutoStat.

Company Profile

The Company is a large U.S. based retailer with over 90 distribution centers serving over 2,000 stores. Many of the distribution centers employ cross docking of products received from suppliers and sorted directly to store-bound trucks. These distribution centers use case conveyor equipment to move boxes of various sizes between the receiving and shipping areas. As the products are received, they are labeled for routing to the individual stores. As part of the 2019 peak season planning process, The Company contracted with Roar Simulation to build a detailed, configurable simulation model to assist The Company in testing equipment changes and to better understand system capabilities.

Model Description & Flow of Operations

An overall view of the model is shown in Figure 1. The model is built to accommodate up to ten (10) input lanes to the conveyor merge. These conveyors come from the receiving area of the facility. The flow rate and case size on each lane is configurable to represent products coming from multiple suppliers. Once a merge lane is full based on photoeye status, the lane is released to the sortation system.

Cartons entering the high speed sorter are diverted down one of over 100 shipping lanes, also configurable. Operators are assigned to unload from multiple shipping lanes. In addition to testing new automation equipment and controls ideas, the model has been used to evaluate staffing plans.

Outputs from the model include the number of cartons merged and sorted each hour and the recirculation rate. When the back end of the conveyor backs up, the next carton to divert into a full lane will recirculate and return to the conveyor merge to be sorted again. When the front end of the conveyor backs up prior to the merge, missed inductions are also recorded as lost capacity.

What Was Learned in Modeling

For the 2019 planning year, the model was used to develop a strategy to increase capacity at a facility in Georgia. 

The team learned that optimal throughput occurs when the number of induction lines feeding into the wedge is minimized, reducing wait times for full slugs ready to be released onto the sorter. This unfortunately reduces accumulation space and increases the frequency of blocked inductions. Therefore, another key takeaway was that optimal throughput also happens when the induction lines are evenly balanced. 

This was not how the distribution center was running in its current state given that the mix of products had changed significantly since these distribution centers first opened. The model was critical to developing and testing these strategies prior to the 2019 peak period. The actual facility results tracked closely with the results of the model.

In preparation for the 2020 peak season, The Company used the model to evaluate ideas for grouping its outbound labor. With improved grouping, The Company hoped to better balance its labor force required for loading truck, and, at the same time, increase the maximum capacity of the facility. 

Planning a Smarter Future

The configurable conveyor model that Roar Simulation built for The Company through AutoMod is a tool that will help analysts test distribution center strategies and remove constraints. 

Providing both an efficiency edge and a money-saving opportunity, the simulation tools will help The Company build new facilities and/or retrofit existing distribution centers because the model framework is flexible and can be applied easily to other automation equipment designs.