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Traditional structures
Very disorganized workspace
Too big material buffer stocks
No experience with Lean Management
- High motivation (at all levels) to change something
- Very long transition periods between the planning phase and the implementation phase because of orders / delivery times. The total duration of the project was 4 instead of the planned 3 months.
- A Result after a six month long roll out was a 43% reduction in lead time in the modernised department
- The investment were amortised within six months
- After the lighthouse, the company was able to modernise additional departments on its own. In total, the lead time decreased by approx. 40%. With the roll-out to additional departments, the company’s financial profits were improved by about 20%.
Approach:
1. Preparation: overall awareness and introduction of demand flow and lean
Involvement of employees in working sessions, training and implementation
2. Groupsessions fabrication (operators from puncing, bending, spot welding, coating parts)
process map (value stream map)
current lay out and material flow
assessing examples of waste
from push to pull
improved lay out and workstation design
implementation (lay out, kanban, workstations, maximum buffer, carriers)
3. Groupsessions assembly (involvement of operators, engineering, proces engineering, management)
- assembly process scheme for a number of products
- improving product design (design for assembly)
- definition of celluar assembly flows (based on product mix, expected numbers of products, demand )
- design of each assembly cell (product carrier, material location, racks, handling of heavy parts, in process Kanban, testing)
- design of workinstructions
- implementation on the shop floor
Traditional structures and lay out (functional)
Very disorganized workspace
Too much (intermediate) material buffer stocks
No experience with Lean Management
Long lead times
Manufacturing by batches (push)
material handling (physical load);
searching for parts
- unplanned overtime work (stress)
- Increase of turnover by 40% (same amount of employees)
Reduction of change over time:
flexible production of small sized batches,
lower work in process
Production is less hectic, no need for overtime work during busy periods (saving up to € 15.000 per year).
2 FTEs fewer are needed during pre-processing
25% fewer assembly hours per machine
Reduction of WIP of around €100.000
ROI of one year
Reduction of physical load
- Communication between engineering and production: Design for assembly and work instructions
Production Manager (Biddle): “The demand flow project has changed the organization of our production enormously, from a traditional production company to a demand-driven production environment. This has significantly increased the involvement of the production employees, because they have to consider their internal customer during the process – that is, the next stage in the process. The first step is to optimize supply for your internal customer, followed by optimizing your own work environment – that raises the interest of employees in the work processes, and therefore their motivation. Lean is not just for production, but actually for the entire order preparation trajectory, including the supply chain.”
There were many customers and their product variants make high variety for the company. So, initially customers having more product demand are considered for pilot study and all the data of the processes was collected. All the processes along the production line were observed and analyzed briefly. The various processes of the different production lines were observed and activity time readings were noted to determine the overall time taken by a process. To avoid human error, we also shoot videos of the complete changeover process 1. Then, verified all activity time readings with videos taken and finalized activity cycle time. Next step after data collection was to analyze the data of various process. Activities are categorized in to 3 types viz. VA operations, NVA operations and NVA but necessary operations, to priorities action plan in order to easy and smooth implementation. After the improvement in the production line, we studied critical machines (having largest set up time) of various production lines and reduced the setup time.
Company have some factories with different capacities located across the world to fulfil requirements of customers in respective region and so on. Company was facing delivery issues though its customers are located nearby to the company. After analyzing material and information flows of all processes by using value stream mapping, few major problems come on surface. One of the critical things was large amount of time spent in changeover activities. Hence we decided to reduce setup time and help them improve production output and timely delivery to the customers.
After the analysis of all the charts, excel sheets, time study and bar graphs, the Kaizen approach was used to eliminate the time consuming factors.
In the End we clustered the improvemts in NVA, NVA but necessary, and VA. Fpr the proction Line 1. We reduced NVW from 16 minutes to 0 minutes. NVA but nevessary wwas reduced von 57 minutes to 14 minutes. The VA-time was not changed.
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• Too big material buffer stocks
• Low visibility and traceability between operations
• Most of existing improvement efforts have focussed on process technology innovations
• Limited experience with Lean for production control
• High motivation (at all levels) to apply other changes to get the best out of process technology improvements
Order sequencing is
the search for a schedule that defines start times of production orders in such
a way that certain objective functions are optimized. The objective in the
Piping production environment at the case company was to minimise average lead times
of the products. Production lines at the company have a higher variety and
lower volume than typical mass production lines. Piping section has 20
workstations, most of them contain one or two identical CNC-machines. Operators
perform a fixed setup at the start of every production order and a variable
changeover depending on the current settings of the machine and the required
settings of the next production order. The used dataset contains 660 different order
types, on average these are produced on only 2 workstations.
The Piping facility is
a flow shop; the flow of production orders between workstations is always in
the same direction. Further important characteristics are the rolling horizon
and the sequence dependent changeover times. New production orders are
continuously added to the system, there is no clearly defined start or end
point. The situation is called dynamic. Further, the changeover time of a
workstation is both dependent on the last produced product type and the next one.
The objective is to find an algorithm that will provide the operators what
production order they need to start next, in a way that minimizes overall lead times
for the production facility.
A lot of variations
exist on the traditional order sequencing problem and a lot of research has
been done about it. A simulation model was built to evaluate several priority rules.
The current sequencing method was implemented to validate the simulation and to
have a reference point to evaluate possible improvements. Currently the
operators combine a First-In-First-Out policy with a minimisation of changeovers.
In general, they select the oldest production orders and within this group they
will minimize the total amount of changeovers. The data obtained from the simulation
was then compared to data from the production facility to validate the model.
The simulation model approximated the real situation, though not with great precision.
The simulation was also validated with a second dataset to confirm its
robustness. The model allows rapid comparison of several priority rules. The
simulation also provided means to optimize small adjustments to the sequencing
algorithm. The model was made as general as possible to allow the company to
evaluate the effect of several possible changes to the production environment,
and to possibly be used for further research to optimise the production
facility.
Scheduling at the
company is dynamic, it happens on a rolling horizon as opposed to the typical situations
in this subject. There is no distinctive start or end point from the schedule
as jobs are continuously added to the system. As a consequence, jobs with an
availability time larger than the current time are unknown. The schedule has to
be reevaluated continuously as new jobs are added to the system. The makespan of
the schedule cannot be defined because of this endless character. The
performance of a schedule will be evaluated by looking at the leadtime of
production orders, which is defined as its completion time minus its
availability time.
Another difference in
comparison to the general job shop problem is the presence of sequence
dependent setup times. That means that the total production times are not known
exactly until the schedule is made. A production order at the shop can only be
started when the Processor is available, and an Operator is ready to start the
production.
Several rules were tested in the company and the best performing
rule was selected. The selected rule assigns to each production order the value
of its changeover time (CO) plus its average processing time per operation
(AVPRO). The next production order to be processed on a workstation, is then
the production order with the lowest value from all available production orders.
In the simulation, this rule decreased the average production leadtime per
order type with more than 20%.
The implementation was started on one workstation. The initial
results were promising; the obtained leadtime reduction of 25% was even larger
than expected from simulation, while the leadtime of a control group lightly
increased. It was expected that the leadtime of order types with a large value
for AVPRO would increase, and this behaviour was observed from the
implementation.
Case Study:
Following goals established for the project:
- Instructions and working methods standardization.
- Training multitask workers.
- Standardize order flows.
- Optimize product flows.
- Implement 5S.
- Manage inventory of components.
- Make better use of space.
During the project implementation, process maps and spaghetti diagram were designed and following assignments determined or accomplished:
- Testing alternatives for laser.
- Setting up customers complaints Indicator.
- Calculating the number of work desks.
- Equipping work desks.
- Designing a new layout.
- Dividing inventories: fast movers at front, slow movers in the back.
- Providing Rack for keys saw machine.
- FIFO system for orders.
Some of the achieved results are:
- Clear status of orders and workloads.
- 5S implementation.
- Smooth product flow.
- Reduction of walking distance.
- - No or limited work instructions.
- - No view on workload, delivery time of orders.
- - Unstructured product flow.
- - A lot of excess material present at work station.
- - A lot of components present on workstation.
- - 10 work stations, for max 4 operators.
Here are some outputs of the projects:
- Reduction of order lead time from 3 weeks to 48 hours
- Reduction of surface area from 101 m2 to 84 m2.
- Reduction of work stations from 10 to 6.
- Substantial reduction of work in process.
Also a to-do list for after the project was proposed:
- Centralize and prioritize the orders.
- Instead of the components keep unassembled cylinders in stock.
- Examining the possibility of electronic data transmission to the laser and key machine.
In 2010, a POLCA-scan took place to assess the suitability of POLCA within the assembly department of Variass Veendam. To reduce variability, an overview of the inter-cell traffic between several cells was designed. Eventually, a schematic overview with the most important POLCA-loops was established. These POLCA-loops capture 91% of all order flows.
Since
the variety of products, production times and production routings are too high
to just use POLCA as it is, the design team of Variass made adjustments to make
POLCA fit for their purpose. They decided to link POLCA cards to cells instead
of different POLCA loops. In addition, it was chosen to use one central POLCA
board, centrally located and accessible to all cells. The information on this
central POLCA board helps to make sequencing and dispatching decisions in the
cells and provides information about the staffing within each cell. A
combination of this information helps the production manager to decide whether
it is necessary to move employees from one cell to another. The figure below shows the central bulletin board which indicates staffing information along with POLCA cards indicating the need for jobs. The manager is pointing to the number of workers in a particular cell.
2. FIFO: the workers were stimulated to focus on the oldest jobs in the on-line scheduling of jobs on the work floor. This principle reduces the variability in throughput times of jobs.
3. TAKT: the time principle was added to the system. The workers should be informed about their productivity: do they realize the manufacturing target of the day?
The workers in the CB unit are responsible for having no more than a certain number of jobs in the system. The daily output of the CB unit, in terms of the number of jobs, indicates the number of jobs that may be released daily by the planning department. Released jobs are made visible in an input buffer. The first operation in the CB unit was punching. At this station, some nesting of jobs was important to save setup time. The puncher picks the best jobs from the input buffer A.
In order to support the workers in the CB unit, a screen is placed at the work floor that gives information about the Work-in-Process level, the FIFO-priority of jobs, and the extent to which the unit realizes the required TAKT-output.
The case study was a longitudinal study, which started in 2010 and is not finished yet, since projects are distributed among the entire organization. The first solution found was to recall the production of standard parts to Assen, to reduce the overall lead time. However, the managers decided to stick to the original production division. They argued good inventory management was enough to realize short lead times for the customer.
The organization started to focus on the administrative processes first. Several MCT maps showed long and varying waiting times in these processes. They started to concentrate on type A and B, to get successful results more easily, to create enthusiasm and support among the employees.
The processes contained four steps, performed in different departments:
1. Sales and customer service
2. Finance
3. Planning
4. Purchasing
The process (1-2-3-4-1) took at least three days, due to several waiting times between the process steps. According to Quick Response Manufacturing, a common solution for this is to organize a Quick Response Office Cell (QROC) for a specific market segment. A QROC is a dedicated, multifunctional team, in which members are closely located to each other. However, the capacity requirements were too low to create a separate QROC for these Type A and B pumps. Therefore they found their own new solution: the QROC light.
A QROC light is similar to a lean production line, in which a small batch of quotes moves between the different departments with a takt time of one hour. The next morning, there is a team meeting, consisting of two people from each department. They discuss divergent topics, such as the priority of orders, a change within the safety stocks or the need for an increase in production capacity. Directly after this meeting, all quotes could be send to the customers.
SPX experimented with several process improvement tools for ten years. The implementation of Lean manufacturing gained considerable attention after the take-over by SPX Process Equipment (USA) in 2007. The organization started to implement Kanban to reduce lead time and inventory. Due to the high-mix, low volume environment in which the organization operates, the implementation resulted in a disappointing outcome. All pumps, approximately 15000 each year, are produced based on a customer order. Due to the endless variation, the managers of location Assen were challenged to find an appropriate solution for the logistic situation.
All products can be divided into different categories, type A, B, C and D. Type A en B are relatively simple pumps, which are produced based on assemble-to-order. The lead time of these types is approximately two to three weeks. Type C and D are pumps with specific requirements, around 40% of the orders. These pumps are produced based on design-to-order. Type C pumps only have some customization (30%). Type D pumps have multiple customer dependent requirements (10%). These projects could last for months.
Customer specific parts are produced in Assen. Approximately 100 employees work at this location. The focus within this location is on speed and flexibility. Generally, all standard and simple parts are ordered and produced in India. In India their focus is mainly on efficiency.
Consequently,
SPX FT has to deal with a high mix, low volume production and a long lead time
for standard parts produced in India. The goal was to organize an organization
which has reliable and repetitive lead times.
The QROC light resulted in a lead time of only one day. The overall MCT changed from 18 to 16 days (a difference of two days in the administrative processes). The companies delivery reliability increased from 76% to 93%.
After this first project, the organization started to focus on Type C and D pumps. There is enough capacity available for these types to create a real QROC, in which people from different disciplines work closely together.
After the takeover, a number of changes were implemented, mainly focused on redefining the markets and focusing on core activities. The core activities of the company were defined as the development, production and sales of centrifugal pumps. The company finished their work for third parties, which previously accounted for 20% of the production capacity. The company also decided not to make displacement pumps anymore. The design, plus the associated markets, was sold to another company. One reason for the sale of this type of pump was the required investments in production (manufacture + assembly). Besides, the nature of the required R&D efforts did not fit with the further development and production of centrifugal pumps.
Furthermore, management decided not to make the standard parts of the centrifugal pumps anymore, but to have them delivered from a sister company in India. This means that SPX Assen only produced small series of parts.
In 1995 the organization was confronted with the consequences of a general economic malaise. The operating profit decreased. The market placed increasingly higher demands and more serious competitors were added. Furthermore, internal operations were under stress due to the deteriorated situation.
In 1997, the organization was taken over by another company. In this case description, we focus on the company’s strategy to refine markets and focus on core activities.
The changes resulted in a significant reduction of the lead times of customer orders from several days (depending on the product type) to one or few days. Due to the choice for only making centrifugal pumps and the increased efficiency in the assembly, the number of employees has been reduced from approximately 160 to only 100 people. This was achieved through natural redundancy of personnel.
The market situation improved considerably is the upcoming years. The company supplied and still supplies high-quality pumps for a wide variety of applications. Often customers do not have a real alternative to the pumps. And if there was an alternative, SPX Assen competes on quality and speed. They are not the cheapest among all the competitors.
In the
course of years, the manufacturing department of the company became also considerably
smaller. The management of the company however decided to keep modern
production equipment and, eventually purchase new machines, in order to produce
special or unique components. These
items are directly delivered to cells. There
is no need for a warehouse between parts manufacture (elsewhere or at home) and
assembly. Only for very large series, which are supplied from India, the
warehouse is used.
After the takeover, a number of changes were implemented. One of the greatest changes was related to the assembly department. In the past, all parts required for an order were picked from the central warehouse and brought to benches where the assembly was carried out by the assembly workers. The parts were located on one or more pallets. The production management has put a lot of effort into reducing the throughput time of the assembly. They basically made an assembly organization in which no time was needed anymore for picking the correct parts. There are a number of assembly cells: a separate cell for each pump family. An assembly cell consists of racks containing parts, placed in a U-shape. The assembly of pumps are performed on carts, trolleys. If the demand for pumps from a certain family increases, more assembly workers can be assigned to the cell, each of them taking care of the assembly of a pump on a trolley. The assembly worker walks with the trolley (or mobile assembly table) along the racks. The fast running parts are on the lower part of the racks, the slow running parts are higher. The stocks of parts are placed high or in the back of the racks. Two bin systems are used to fill the rack with new, standard, modules. Due to the modular product structure, a pumping family comprises a large number of variants. The batch sizes of assembly orders are small (1 - 3).
In 1995 the organization was confronted with the consequences of a general economic malaise. The operating profit decreased. The market placed increasingly higher demands and more serious competitors were added. Furthermore, internal operations were under stress due to the deteriorated situation.
In 1997, the organization was taken over by another company. In this case description, we focus on the company’s strategy to reduce assembly lead time by reorganizing the assembly department layout (U-shape) and way of working.
By using this new assembly organization, the picking of components from the central warehouse has not to be done anymore in the lead time of orders. Furthermore, assembly time has been reduced by means of a smart 5S design of the assembly trolleys.
The changes in component manufacture and assembly also resulted in a significant change in the layout of the company. There is more space in use for the assembly.
Finally, this new way of working makes it easy to change the amount of workers that are assigned to different cells, according to the demand of the pumps. Additionally, when a specific type needs to be produced in a large batch, there is the opportunity to work with two persons in this u-shaped cell, see figure below.
- Too big material buffer stocks
- Low visibility and traceability between operations
- Most of existing improvement efforts have focussed on process technology innovations
- Experience with Lean for production control but significant room remained for achieving its full benefits
- High motivation (at all levels) to apply other changes to get the best out of process technology improvements