Kitting For Custom Job Shops
Kitting is a system that presents required components and tools to an assembly area in an organized method in order to obtain efficiencies.
By: Bill Brockhurst
LEAD Associate - Lean Advisors Inc.
What is Kitting?
Kitting, in manufacturing settings is a system that presents required components and tools to an assembly area in an organized method in order to obtain efficiencies. All items are presented in a logical order so they can be removed from the container as quickly as possible without damage. It is important to keep it simple and the kit itself is structured or laid out in a predetermined and effective way. To maintain control and standardization, there should not be any change to the kit by any individual unless the team has approved the modification and the new change should lead to an improvement in the end-to-end process.
What are the Benefits of Kitting?
Kitting makes it easier to train operators and reduces the time it takes to bring operators up to takt time. This system will provide the opportunity to eliminate the operator's frustration of searching for the correct component by presenting all items in a consistent manner. Kits will reduce rework cost by protecting components from damage and eliminating the possibility for missing components. The number of kits completed will also visually measure the amount of work completed. Having the exact number of parts required to complete a process in the kit makes it very obvious that if a component is left over after the process is finished then there is a problem. This allows you the opportunity initiate an investigation into the root cause, and then changes can be managed before mistakes impact your customers.
Maximizing the Benefits of the Kit
Other lean concepts can be incorporated to receive the maximum benefits from kitting. If you apply Poka Yoke to the process of filling the kit, you have a spot for only the required components and the kit will not be released to the assembly operator until all required components are in place. Kitting when combined with Standardized Work instructions will give you a way to sustain the gains in efficiencies you have achieved with kitting.
Standardized Work Practices (right handed operators)
1. Remove one washer with right hand
2. Remove one screw with left hand
3. Insert screw into washer
4. Insert screw with washer into connector and insert into hole 1
5. Remove one lock washer with left hand
Applying the Concept of Kitting in a Job Shop
How does kitting apply in a custom job shop? The challenge in the plastic injection mould industry (custom job shop) occurs at the final assembly stage. How do you take the large variance that occurs from job to job and come out with a standardized process? Some of the difficult challenges that come into play at final assembly start from the time the job kicks off and the design engineers develop the plastic injection mould that will be used for the creation of the plastic part that the customer requires. The bill of material is created concurrent with the design of the required components. After several stages of design and customer approvals, the final bill of material list is then released to purchasing.
Some of the components needed to put a mould together are off-the-shelf, some are custom orders, and some are one-of-a-kind components that are built to precise standards. Parts arrive over long, interval, various, and sometimes unpredictable times. Once received, the parts are staged for assembly. To complicate things even more, you have to track the arrival of components to verify that the correct number of components have been received and staged in a manner to allow easy retrieval without damage, or being misplaced.
A common solution is to use a box to store all components including very expensive components. This method creates the practice of going to look and see if the required part is available. Hunting through the parts for the part required and putting back the parts that will be required later in the build can lead to total frustration and damage.
The Importance Of Value Stream Mapping
The solution became clear once the Value Stream Map of the process was completed. One of the issues to be resolved was the consumables and off-the-shelf parts. These are the components that are readily available and inexpensive, components like screws and water hose fittings. We decided we needed to develop a supplier-controlled supermarket for off-the-shelf parts. These components were set-in-order in a cabinet at each value stream with a set limit on the number of parts. The supplier would arrive every Monday to record usage over the previous week and create a purchase order to replace used parts.
Value Stream Managers would verify the number used on the job(s) from the pervious week and hand deliver the request to purchase directly to the purchasing manager to create a PO number. The supplier would then restock components on Tuesday. The surprising part was after a short time the Value Stream Mapping verification and the creation of a PO number was determined to be waste and the supplier now goes directly from determining usage to restocking the cabinets without the need for wasted paper. With a supplier-controlled supermarket the supplier only invoices after the items are used creating better cash flow. The consumable components would be pulled and staged just before assembly would start.
All remaining components on the bill of material is ordered by specific jobs and purchasing asks suppliers to deliver the component when it was required for assembly. In some cases where we lacked confidence in suppliers to meet the delivery date, we asked for the components earlier until we gained confidence in the supplier to meet delivery dates.
What does Kitting do to your Value Stream Map?
Kitting can remove a significant amount of waste, which of course will reduce your lead-time. Looking at the process times in the Value Stream Map above, you can see that the kit impacted process time and not cycle time. Cycle time stays the same because you are removing waste around the process and not changing the process. Lead-time can be reduced by concentrating on the waste around the operator and not on the operator himself. In this case, 2 days of build time was removed. Savings in administration (purchasing, damage reductions, etc.) were also realized. Improvement in process time of 41 hrs was accomplished by removing muda (walking and searching for components). Regular scheduled hours are based on 24hr days, this means 139 hrs in the Current State is approximately 7 days of processing time. With the implementation of the Future State, the process time was reduced to 98 hrs or approximately 5 days processing time in final assembly.
Final Assembly Kaizen
The next step identified in the Implementation plan was to kaizen Final Assembly. This process included a large number of activities and was very difficult to manage. Mapping the product made it extremely easy to see an opportunity to kaizen the process to improve the employee's ability to complete the tasks more efficiently. Final assembly was broken down into elements of assembly and each element was set-up in a designated area adjusted to the next process creating a flow through final assembly. Without the moving the components to the newly developed process area the employee was required to walk back and forth to the staging area. This was highly ineffective. To take advantage of the increase in flow, it was decided that a method was needed to create an efficient way to move organized parts from one area to the next. To increase the hands on 'steel time' (an industry term for value added to the steel), there was a need for a lean methodology tool to be used.
This was a great opportunity to apply the lean tool of kitting. The picture above shows an example of how the lean tool of kitting, can be adapted to achieve benefits in a custom job shop environment. Hanging the difficult ones to stored is an option. Open containers allow easy access and visibility. After the Map was competed, you understand the problem and a proper solution can be implemented.