Container Filling and Bulk Load Scheduling
The result of the blending production is a finished product that can be sold either as a bulk product – transported to customers by ships, tank trains or tank trucks – or as a filled and packaged product.
Transports by ship or train often have a fixed schedule – based on due dates of bulk sales orders – that has to be met by the blending department by provision of the required bulk products at defined times, usually in large quantities in assigned storage tanks. As these schedules cannot usually be flexibly changed and are often repetitive, there is little benefit to gain from a close coordination with the blend production schedule.
Transports by tank trucks as well as production of filled containers, however, need a higher flexibility; establishment of truck loading and filling schedules is an important challenge for the production planning department, where significant benefits can be gained from a close coordination with the blend production schedule.
Similar business processes are used by other companies producing liquid products that can be sold as bulk or packaged products, as well as, for example, by companies who produce blended wax-related products. These may have a forming operation as part of their filling process (e.g. creation of powders, pastilles or blocks), but that rarely needs extra consideration from the scheduling point of view.
"Blending and filling planning" departments are responsible to schedule the blending, filling and tank truck loading over a short-term planning horizon – based on sales orders and strategic monthly planning figures – with a high rate of flexibility due to volatile sales requirements.
Their business processes include scheduling of filling lines and tank truck load points and monitoring of tank allocation for bulk product storage tank farms under consideration of limited tank capacities.
ORSOFT Manufacturing Workbench supports these business processes with the combination of standard APS and MES functions and specific functions that take the oil industries' special requirements into account.
Quite often, the supply chain of blending and filling / loading is handled by the same planner for a certain range of products. First, the blend order schedule is established. This gives the time range for the filling / loading order, which is determined by the time the bulk product is available in the storage tank (and approved by quality inspection). It also gives the time when the next blend order will start filling the storage tank again, perhaps with a different product. Based on this time range, the filling / loading order is scheduled.
The Manufacturing Execution (MES) module of the ORSOFT Manufacturing Workbench is used for short term scheduling and rescheduling and to monitor the production execution progress of the blending and filling. For filling, it includes optimization of sequences with fewer changeovers, selection of appropriate filling unit with regard to container size and filling capacity, availability of empty containers and packaging materials, and availability of storage capacity for container products (cans, barrels etc.) or 'just in time' loading of trailer tanks or tank wagons.
The ORSOFT Manufacturing Workbench supports the planning process to find the best schedule within constraints such as due dates of sales orders or tank capacity, with options for pull production (starting from the demands) and push production (starting from bulk blends that need to be processed and filled soon). The software checks the availability of bulk components on tank level and in total stock as well as the availability of blending equipment and filling lines. It visualizes the production progress status.
Detailed Scheduling of Container Filling Lines
Blended products are often sold to end customers in small quantities, packaged in containers of various forms and sizes.
Container filling is often planned as a mixture of make-to-order production based on sales orders and make-to-stock production based on sales forecasts.
Filling process orders are used to handle the production planning and execution for both production scenarios. They need to be scheduled in close coordination with respective blend process orders in terms of time and storage tank used.
A filling order is scheduled on a container filling line. It considers not only the capacity of the filling line, but also tries to achieve a good sequence on the filling line with fewer changeovers (similar product group, same container form factor etc.).
A container filling line scheduling workframe within the ORSOFT Manufacturing Workbench Gantt charts for filling lines, combined with Gantt charts and histograms for source storage tank allocation and filling order lists, supports the planner in maintaining filling schedules and monitoring resulting allocations and stock levels at the finished bulk products tank farm.
The concept of checkmark indicators makes the software convenient to use. All filling orders containing a checkmark for 'in time delivery', 'available to promise' and 'capable to promise' are scheduled correctly and do not require any additional planning treatment. The planner can concentrate on only the remaining few scheduled filling orders with missing checkmarks. These orders can be selected by a single mouse click.
The screenshot (click to enlarge) shows a filling workframe with a Gantt chart visualization of the filling lines in the upper window. Moving the mouse pointer to a bar representing one filling order will cause a window with all the detailed information about this order to appear. The medium window shows all filling orders with order numbers (taken from the leading ERP system), product name, batch size, filling line, input tank and check marks for 'available to promise' and 'capable to promise' checks, as well as pegged information regarding the corresponding blend order to produce the source bulk material for the filling order. The lower window shows a special visualization for a single filling order, displaying its filling line and its sourcing tank in a higher zoom level to display the entire day. This can be used to reschedule the filling order to synchronize exactly with blend orders and load allocations on the same source tank.
Time Slot Scheduling of Bulk Loading Points
A large part of the delivery of bulk blended products to customers is done with tank trucks. These are often operated by many different forwarding companies – either on behalf of the customer or as independent companies serving specific regions.
Tank Trucks are loaded at specific load points from a specific storage tank containing the desired product, often in a single batch that has been produced by the blend department for a specific sales order.
Unlike make-to-order container filling, where it is quite normal to use filling process orders in an ERP system to handle the production planning and execution in addition to sales orders for the filled product (because it is often combined with make-to-stock container filling), many companies do not want to use extra process orders in an ERP system to handle the planning and execution for make-to-order bulk loading. This is because of the resulting "overhead" of synchronizing changes of the sales order with the load process order, which often leads to a "model gap" in the supply chain. By extending the model of a sales order with a subordinate object "load allocation" – with references to load point, source storage tank and load time (slot) – this "model gap" can be closed and the "overhead" can be avoided.
On the one hand, the load points can be a bottleneck if many trucks – possibly from different forwarding companies – arrive at the same time and must queue at the load point for loading. On the other hand, the storage tanks can be a bottleneck if the truck cannot be loaded – either because it arrives late or because it has to queue – and thus the storage tank cannot be depleted fast enough to reuse it for the next blend order.
To de-bottleneck the bulk loading while considering the uncertainties of road-based traffic, companies have started to introduce "time slots" for the forwarding companies, similar to those used in airspace traffic, which are more precise than merely the material availability date from the sales order.
The quantity of an individual tank truck load allocation determines the duration of the loading and thus the capacity requirement for the load point as well as the duration of the discharge of the storage tank.
Load point scheduling may use these "time slots" in order to establish a load schedule under consideration of total load point capacity in the time slot and of planned availability and allocation of storage tanks.
Each tank truck load allocation – which already has a material availability date, a source storage tank and a load point – can be interactively assigned to a time slot of the load point on the material availability date. By summing the duration of all assigned tank truck load allocations in a time slot, a capacity check can easily prevent "overbooking" of a slot.
Once the load schedule has been established, the blending department will also automatically receive a schedule for depletion of their storage tanks – with the accurate time slot – and can schedule the next blend orders that will use these storage tanks.
A load point scheduling workframe within the ORSOFT Manufacturing Workbench – which uses Gantt charts for load points to visualize time slots, combines Gantt charts and histograms for source storage tank allocation and tank truck load allocation lists – supports the planner in maintaining load point schedules and monitoring resulting allocations and stock levels at the finished bulk products tank farm.
In addition to standard functions for scheduling a tank truck load allocation at a given time (similar to scheduling of a process order on a device), the software provides functions to schedule a tank truck load allocation in a given time slot and "shuffle" already existing tank truck load allocations within that slot in order to have an uninterrupted sequence and thus a visual indication of the capacity load of the slot in a Gantt chart.
The screenshot (click to enlarge) shows a loading workframe with a Gantt chart visualization of the load points in the upper window. Moving the mouse pointer to a bar representing one load allocation will cause a window with all detailed information about this allocation to appear. The medium window shows all tank truck load allocation with order numbers (taken from the leading ERP system), product name, batch size, load point, input tank and check marks for "available to promise" and "capable to promise" checks – as well as pegged information regarding the corresponding blend order to produce the source bulk material for the tank truck load allocation. The lower window shows a special visualization for a single tank truck load allocation, displaying its load point and its sourcing tank in a higher zoom level to show the whole day. This can be used to reschedule the tank truck load allocation exactly to synchronize with blend orders and filling orders on the same source tank.