Measuring the batch cycle for consistent performance
Plant throughput is a key factor for maximizing profitability. The ability to establish the production capacity of each plant then maintaining that capacity day after day is an absolute requirement to protect your bottom line and achieve on-time delivery goals. A reliable concrete supplier needs repeatable results within each stage of the production process. This document identifies the key factors within each stage of production that must be measured and maintained.
The Ready-Mix Concrete Production Cycle
The concrete production process requires six to eight separate stages as shown above. The first four stages of production are the same for both dry batch and wet mix plants. Beyond that point the process splits depending on wet mix versus dry batch.
The ‘PRODUCTION CYCLE TIME’ itself is easy to witness; the time elapsed between one truck and a subsequent truck leaving the plant loading area is the single best indicator of how fast the entire system is operating. The ability for trucks to be loaded and get on the way to the job is dependent upon many steps within the production process. Measuring actual results as compared to the benchmarks, then implementing appropriate action when the benchmarks aren’t met is the only way to ensure reliable production throughput. Measuring the batch cycle for consistent performance day in and day out is necessary to have confidence that production goals for your largest jobs will successfully be met without disruptions to your normal operations.
Measuring the Production Cycle
The following table outlines what goals (or benchmarks) should in place and monitored to ensure that valuable seconds are not forever lost from load to load and day after day.
| Process Stage |
Measurement |
| Ticket Stacking and Load Prepare |
Minimizing the number of actions required from the plant operator is the first opportunity to ensure your production process stays on track. If the ticket is sent from the Dispatch System but the weigh up process gets delayed due to the operator’s work (i.e., adjusting admixes, trimming water, corralling trucks) valuable seconds can be lost. Benchmarks: Measure the time between the arrival of a ticket on the batch system and the start of the loading process to ensure that loads are started when needed. |
| Weigh Up |
The dry material weigh up is often one of the longest duration process steps within a load. Depending on the condition of the plant and the tuning of the automation system this stage can make or break the load production cycle. Everyone accepts that batch plant production can vary for a variety of reasons… inconsistent cementitious material flows, empty aggregate bins, poor tuning which causes excessive feed cycles (i.e. ‘jogging’), or delays due to the operator being presented with tolerance errors. Benchmarks: Establish material weigh up duration goals specific to load size ranges (small, medium, large.) Monitor the ability of the plant to meet these goals. When the goals are not met, review the plant hardware, the batch panel parameters, and even the material handling/loader operator efficiency to get production duration time back to the goal. |
Dry Batch Plants:
| Wait For Truck |
An often hidden lost of time can be when the plant has a load in the scales ready to go, but the truck is not in the loading position, or the drum is not. Benchmarks: Measure the time between the completion of dry material weigh up and the start of the loading process to ensure that trucks are in position on time. |
| Charge Truck |
The dry material movement from the scales to the truck is another of the longest processes within a load. Like the weigh up cycle, the condition of the plant and the tuning of the automation system this stage can make or break the load production cycle time. Benchmarks: Establish a benchmark and then measure the time between the start of the first scale discharge to the truck to the completion of the wash down water. This time is likely to vary depending upon load size (small, medium, large.) That said, the truck charge phase of the production process can easily creep up over time with significant impact on production cycle time. Keeping tabs on this time is important to maintaining maximum plant production. |
| Slump Adjust |
At many plants, after all the materials are in the truck an immense amount of time is lost due to the need to add water to achieve desired slump. The ‘correct’ slump at the plant for each ticket is often hard to identify depending on the mix, the operator, the driver, and distance to the job. Benchmarks: Establish an acceptable amount of time between the completion of the truck charge process by the batch panel and the time the truck moves to the washdown rack. Add dry temper water counter to develop a profile of what mixes and what operators consume the most time to achieve desired slump. Pass this information to QC so mix adjustments can be made. |
Wet Batch Plants:
| Process Stage | Measurement |
| Charge Mixer |
This process is generally easy to predict and does not vary much. Nonetheless, it should be monitored. Benchmarks: Measure the time between the start of the first material into the mixer and the completion of the last. |
| Mix Time |
The wet mix time is often specified by regulatory agencies and/or experience.
|
| Slump Adjust |
At many plants, after all the materials and the mix time is completed, an immense amount of time is lost due to the need to add water to achieve desired slump. The ‘correct’ slump at the plant for each ticket is often hard to identify depending on the mix, the operator, the driver, and distance to the job. Benchmarks: Establish an acceptable amount of time between the completion of the mix time complete and the time the mixer is emptied. Add temper water counter to develop a profile of what mixes and what operators consume the most time to achieve |
| Mixer Empty |
This final stage of the production process can extend the overall load cycle time if the operator is too conservative when loading the truck. Benchmarks: Monitor the operator performance so mixer empty |
Final considerations
Predictable and consistent ready-mix concrete production volume requires the efficient execution of many process steps. Without a process that measures the batch cycle for consistent performance a 10-20 percent reduction in production is a distinct possibility. Evaluate your production system software to learn what analytic tools are available to monitor both real time performance and long-term trends including side by side plant comparison. These systems can provide automatic monitoring of your production processes and alert you to out-of compliance issues that will cost you time and money.
As a key architect behind COMMANDbatch and REDI-VIEW, Randy Willaman brings decades of hands-on experience with batching systems. Through his posts, Randy shares his unparalleled expertise and insights with concrete producers looking to maximize their system's potential. Learn more about his services here.
