The Just-In-Sequence (JIS) methodology is an evolution of the Just-In-Time (JIT) concept applied to production logistics. In today’s automotive environment, where each vehicle is made to order with multiple configuration options, JIS has become essential for synchronizing part deliveries with the assembly line. Below, we explain what JIS is, how it works, and how it differs from JIT.
What is Just-In-Sequence (JIS)?
Just-In-Sequence (JIS) is a component supply system for production in which parts are delivered not only just in time, but also in the exact sequence in which they will be assembled. In other words, the supplier (for example, a Tier 1 supplier in the automotive supply chain) sends parts directly to the manufacturer’s (OEM) assembly line at the required time and in the precise order in which they are needed. This means that line workers don’t have to choose between parts or search through inventories; they simply take the next part in the supply queue and install it. This simplifies and speeds up the production process, eliminating unnecessary handling and delays.
In the automotive industry, JIS is also known as Sequential Parts Delivery or In-Line Vehicle Sequencing (ILVS), as it is used to synchronize components (such as doors, seats, dashboards, bumpers, etc.) with the specific production sequence of vehicles on the final assembly line.
Differences between Just-In-Sequence (JIS) and Just-In-Time (JIT)
The JIS concept is closely related to Just In Time (JIT), but they are not the same. Both systems aim to optimize production efficiency by reducing inventories and delivering only what is needed, exactly when it is needed. However, JIS takes things a step further by adding the requirement of exact sequencing to the timely delivery:
- Just-In-Time (JIT): Focuses on ensuring that parts arrive precisely when needed, avoiding excess stock. It does not require a specific order of part arrival-just that the parts are available on time for assembly.
- Just-In-Sequence (JIS): In addition to being “on time,” parts must arrive in the exact order of assembly. That means logistics must meet both the timing and the precise sequence of production.
This distinction is reflected in how the plant operates:
- In a traditional JIT system, line workers have a small batch of parts available and must choose the right part for the next vehicle. Although inventory is limited (minimizing the search), the operator still needs to select the correct part for each car.
- In a JIS system, the operator does not need to make decisions about which part to install next; they simply take the next part in the delivered sequence, as it has already been pre-sorted according to the assembly plan. This eliminates the risk of selection errors and saves time, since the decision was already made during the logistics phase.
In summary: JIT ensures the right part arrives on time, while JIS ensures it arrives on time and in the correct order. All JIS is JIT, but not all JIT is JIS.
How does Just-In-Sequence work in the automotive industry?
Implementing Just-In-Sequence in an automotive plant requires aligning a supplier’s production with the manufacturer’s assembly schedule with high precision. Here’s how a typical JIS flow works in the automotive sector when the part is produced by a Tier 1 supplier:
1. Sequencing based on vehicle production
The OEM establishes the production order for vehicles on the final line (e.g., a red model X, followed by a blue model Y, then a black model X, etc.). This sequence is frozen several hours before actual assembly—typically about 4 hours—and communicated to JIS suppliers. In the industry, this planned order is known as the “pearl chain” (Perlenkette in German).
2. Transmission of the plan to the supplier (Tier 1)
Once the assembly sequence is defined, the OEM sends the Tier 1 supplier the details of which part is needed for each vehicle and when it should be delivered. This information is transmitted via EDI systems or real-time collaborative platforms. For instance, if the supplier produces seats, it will receive a sequenced order such as: vehicle 1 (red) – black leather seats; vehicle 2 (blue) – gray fabric seats; and so on.
3. Sequenced production or picking
The Tier 1 supplier adjusts its production or picking to prepare the parts in the exact required order. They may produce parts directly in sequence or retrieve them from inventory in that order (pick/pack to sequence). Each part is labeled or identified to ensure it matches the assigned vehicle and its position in the sequence.
4. Synchronized JIS delivery
Parts are sent to the OEM just in time, while maintaining their sequence throughout transport. Since the supplier is usually nearby (often in a supplier park), transit time is minimal. Parts typically travel in containers, racks, or systems specifically designed to preserve the sequence all the way to the assembly line.
5. Consumption on the assembly line
Parts arrive just in time and in the exact order in which the vehicles are assembled. For example, if doors are being installed, the red door must be ready for the red car, followed by the blue door for the blue car, and so on. Thanks to synchronized sequencing, the operator simply takes the next part—no need to verify or search—speeding up assembly and preventing errors.
JIS is especially used for highly customized parts such as seats, panels, dashboards, painted bumpers, or engines—components where each vehicle requires a specific configuration. It is not used for standard or high-volume parts, where the complexity of sequencing doesn’t offer a worthwhile benefit.
It’s also worth noting that JIS is not applied exclusively between a Tier 1 supplier and an OEM. JIS can also be implemented internally within an OEM plant, where certain components are produced or prepared on-site in the exact sequence of assembly. In such cases, the parts are produced or configured according to the planned assembly order and delivered in direct sequence to the next consumption point or final assembly line, without the need for storage or re-sorting.
Technical and logistical requirements to implement JIS
Achieving a functional JIS system requires meeting several key technical and operational conditions:
- Stable Production Sequence: Whether between companies or within the same plant, JIS requires a fixed assembly sequence over a defined period. If production order changes last-minute, it disrupts the system’s logic and forces resequencing.
- Real-Time Communication and Integrated IT Systems: Accurate transmission of the sequence to the next area—whether a supplier or internal workshop—must be done through connected systems (EDI, MES, or collaborative platforms). Technologies like barcodes and RFID help verify each part’s position and vehicle match.
- Synchronized Transportation and Material Handling: Parts must be moved without breaking the sequence, both internally and externally. This is achieved using overhead conveyors, numbered carts, or dedicated racks that ensure a continuous FIFO flow from source to consumption point.
- Responsiveness to Variations: Even with solid planning, issues may arise (reworks, defective parts, line mismatches). A JIS system must include mechanisms to reorganize the sequence—via intermediate buffers, dedicated personnel, or nearby sequencing centers—to ensure continuous flow.
In short, the success of JIS relies heavily on robust planning and control infrastructure. The plant must operate like a Swiss watch, with reliable forecasting, firm short-term production orders, and agile logistics systems. Any weak link—whether it’s underperforming IT, delayed information, or unreliable transportation—can jeopardize the sequence.
Automation and error-free sequencing
Just In Sequence is a key tool for those seeking to optimize costs, reduce lead times, and improve quality in complex manufacturing environments. Its adoption marks the difference between a reactive plant and a highly synchronized, efficient operation.
In our next article, we will dive deeper into a crucial element for maintaining intact sequencing: overhead conveyors. These automated solutions allow each part to be delivered to the right place at the exact time, with no delays or disruptions.
Are you considering implementing JIS or upgrading your intralogistics system? Talk to our team and discover how we can help.