IOT-BASED IMPROVEMENTS IN HOME APPLIANCE MANUFACTURING AT HITACHI GLS
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FEATURED ARTICLES Smart Life Solutions for People Everywhere
IoT-based Improvements in Home
Appliance Manufacturing at Hitachi GLS
At the same time as the manufacturing industry is experiencing major changes brought
about by factors such as the globalization of markets, worsening labor shortages, and
reforms to working practices, another global trend within the industry is the consider-
able activity taking place in relation to the use of digital tools. This includes a variety of
initiatives in Japan based on the concepts of Society 5.0 and the Industrial Value Chain
Initiative. With an emphasis on cell production and using its Lifestyle Home Appliances
Unit as a model, the Products Division of Hitachi Global Life Solutions, Inc. has been
adopting Internet-of-Things systems based on the concepts of enhancing transparency
and connectivity while reducing reliance on particular individuals to reform its manufac-
turing practices in ways that will enhance total supply chain management. This article
describes these improvements.
Nobuhiro Ishida
Toshiki Ishida
sales. This work has been underpinned by the follow-
ing three concepts.
1. Introduction (1) Transparency
The ability for all staff to determine in real time
While retaining an emphasis on cell production, the whether or not production is running smoothly and
reforms to manufacturing practices at Hitachi Global to respond promptly when problems arise.
Life Solutions, Inc. (Hitachi GLS) have combined (2) Connectivity
greater transparency with cell automation and system- The ability to operate production in an optimal
wide optimization of the links between individual manner in terms of the overall process, linking objects
processes as well as the enhancement of efficiency and processes automatically, and bringing the associ-
by getting rid of process steps that do not add any ated data together in information systems.
value or by making improvements or eliminating bar- (3) Elimination of reliance on particular individuals
riers and bottlenecks. The Monozukuri World No. 1 The automation of tasks that rely on particular indi-
Project launched in FY2017 has involved the develop- viduals or that are not best undertaken by people.
ment of proprietary production techniques suitable for The aim is to enhance manufacturing capabilities
wider use and work on establishing optimal systems by using the Internet of Things (IoT) to put these
for high-volume production that facilitate increased concepts into practice.
90.for the sharing of ideas as well as staff development
2. Progress of Reforms to and the fostering of an improvement-oriented cul-
Manufacturing Practices ture through a workplace-led approach. This includes
each of the sites presenting improvement activities at
2. 1 regular meetings attended by senior management and
Cell Production holding GLS Production Innovation (G.P.I.) working
In an environment where product lifecycles are short groups for workplace improvement.
and where home appliances are produced in anticipa-
tion of future sales, the risks are that a slow response
to changing sales trends will result in potential sales 3. Manufacturing IoT
being lost when demand spikes or excess inventory
building up when sales are lower than expected. The Use of IT in the reform of manufacturing practices
aim of cell production is to establish manufactur- has in the past been done in a piecemeal manner, with
ing practices that are both efficient and able to deal activities seeking to provide more transparency in the
with fluctuations in production volumes, reducing manufacturing workplace, its management, the analy-
the quantity of work in progress held between and sis of operations, and so on. However, there is a need
within processes and minimizing both lost time when to optimize operations across multiple sites and utilize
switching production between different models and IoT technology to enhance the production systems
holding costs when work in progress is held up. that monitor and automate all of the steps from the
The Lifestyle Home Appliances Unit at Hitachi machining of parts to sub-assembly manufacturing,
GLS introduced cell production in earnest in 2003 product assembly, inspection, and dispatch, as well as
and has achieved dramatic improvements in pro- the management of the four elements of manufactur-
ductivity by adopting the practice for all of its varied ing (4M): men, machines, materials, and methods,
product range, which extends from washer/dryers based on orders and production planning. Hitachi
to vacuum cleaners, cooking appliances, and light- GLS has consolidated the work being done on this
ing. The unit’s 15-plus years of experience with the within the Monozukuri World No. 1 Project under
practice has included winning a Nikkei Monozukuri the banner of “manufacturing IoT.”
Award in 2008 for a proprietary cell production The aim is to develop systems that will maintain
technique for large home appliances such as front- optimal safety, quality, delivery, and cost (SQDC) by
loading washer/dryer cells and refrigerator and water automating the preparation and updating of produc-
heater cells. tion plans that depend on the expertise of specific
members of staff; handling attendance management,
2. 2 which is complicated by the diversity of ways in which
Monozukuri World No. 1 Project people are employed in the manufacturing workplace;
Hitachi GLS has been running its Monozukuri sharing information for safety, quality, and efficiency
World No. 1 Project at all of its sites since FY2017, improvement; and providing real-time information
including at overseas operations. The project seeks to on things like equipment operation. Although system
improve production efficiency and reduce lead time, development is largely undertaken in-house, systems
with the three key concepts listed above playing a such as those for automatically generating produc-
central role. Phase two of the project, which com- tion plans are developed jointly with the Center for
menced in FY2019, involves the use of automation Technology Innovation – Production Engineering of
and the adoption of new systems to improve efficiency Hitachi Research & Development Group. In either
so as to achieve the 2021 Mid-term Management case, the systems have been put in place through a
Plan. The project is intended to raise the standard bottom-up approach that is able to incorporate the
of manufacturing across Hitachi GLS by means of knowledge held in the workplace in a flexible manner,
activities that run across all worksites and provide taking account of compatibility with core business
Hitachi Review Vol. 69, No. 1 90–91 91.systems and the ability to be extended to other opera- The solution to these challenges is the automatic
tions at the same site. production planning system, which is made up of an
The following sections present examples modeled automatic detailed scheduling system that automati-
on the workplace where front-loading washer dry- cally generates production plans for finished products
ers are manufactured. These front-loading washer and an internal production scheduler that generates
dryers are a major product for the Lifestyle Home production plans for parts manufactured in-house.
Appliances Unit. The current intention is to extend (1) Automatic detailed scheduling system
this work to other products and other sites. This scheduler uses the monthly master production
plan as a basis for generating detailed daily plans and
3. 1 hourly plans that look four days ahead. In doing so,
Automatic Production Planning System it automatically generates optimal production plans
The system is intended to provide the flexibility to that ensure efficient switching between models while
keep pace with fluctuations in market demand and also taking into account product delivery schedules
the rate of production by automating the prepara- and the management of worker overtime.
tion and updating of production plans that previously Work is currently underway on extending its use
depended on the expertise of specific members of staff to the planning of refrigerator production at the
and to rationalize auxiliary tasks. Refrigeration & Heating Home Appliances Unit
A background factor was that, because the Lifestyle (see Figure 1).
Home Appliances Unit had a large amount of on-site (2) Internal production scheduler
production machinery, a result of producing so many of This scheduler supports the most efficient use of
its components itself, there was a heavy workload associ- plant and human resources by synchronizing with
ated with the production planning needed to keep work finished product production, determining monthly
in progress to a minimum while also ensuring a reliable work assignments, the automatic formulation of parts
flow of parts to the assembly line and maintaining a production plans, and the issuing of materials pro-
high level of utilization in the operation of this plant. curement orders as well as raising alarms for changes
Figure 1 — Automatic Detailed Scheduling System
The figure shows an overview of the system and its functions. To automate the process, the different scheduling methods used for different products
are defined as parameters.
■ Overview
Automated system for
■ Main functions
(1) Calendar management and overtime planning
Warn if maximum
scheduling which models Enter daily overtime exceeded
Scheduler ■ March 2018
to produce No. of days when overtime required
overtime
03/01 (Thur.) 03/02 (Fri.) hours
Confirm and modify 2h: 10 days Cycle time 59 (s) Production
9965
Total
(no. units)
3h: 5 days
(Simplified) PSI Hourly
capacity
Planned
9513 453 453
Hourly capacity: 453 overtime 35 2 3
(2) Detailed scheduling
Determine which models GUI Color Generate daily production plans
Appliance model 08 09 10 11 12
to produce scheme in accordance with given rules
XXXXXX N 60 445 355
Values can also be
Detailed scheduling OOOOOO S … 240 280
entered manually
Schedule of which models Overtime engine AAAAAA N 535 15
to produce required
(3) Production volume management/four-day-ahead schedule
DB access engine Collect data on and manage
Color
Appliance model
scheme
19 20 21 22 23 24 production volume
Manufacturing Copy XXXXXX N 299 1 339 422
instructions … Prepare schedule looking four
OOOOOO S 173 2 360 days ahead based on incoming
Scheduler* Update Detailed
Procurement AAAAAA N 32 694 159 goods for the month
schedule DB
instructions Detailed
master Master Detailed Master (4) Determine which models to produce
data 000 Shift
In-house production schedule master data
Product code Model Total number to be produced Planned production volume 000
production
management schedule YYYYYYYY XXXXXX 1800 1800 000
00
BBBBBBBB AAAAAA 1800 1800
Schedule 0 to conveyors
for next Overall Schedule Overall
schedule for next Product code Model Total number to be produced Planned production volume
000
000 with excess
four days schedule YYYYYYYY XXXXXX 1800 0
four days
000
00 capacity
BBBBBBBB AAAAAA 1800 0 0
PSI: production sales inventory GUI: graphical user interface DB: database
*Existing production scheduler used at Lifestyle Home Appliances Unit
92.FEATURED ARTICLES
Figure 2 — Internal Production Scheduler
The figure shows a block diagram of the internal production scheduler and example screens. In addition to work schedules, the system also generates
shift rosters.
■ Main functions Block diagram of internal production scheduler
Final assembly
Problems with past practices
schedule
(1) Production assignment and • Each line was scheduled Hourly
Detailed Management
manually Monthly
(daily)
schedule
of inventory
planning (monthly) • Large amounts of work in schedule
schedule
looking four
levels
days ahead
(2) Parts production schedule progress due to poor
(daily and hourly) synchronization between
(3) Worker shift rosters appliance assembly and parts
(3) Molding (5) Molding (6)
Parts schedule
manufacturing machine schedule machine schedule Statistics
(4) Materials procurement orders • Unavailability of parts when (1) Allocated
(daily) (hourly) on
to production
(5) KPIs needed resulting in overtime (N + 2 months) utilization
(2) Worker and defect
■ Features
• Schedules take account of detailed constraints affecting each line
assignment
(4) Materials
allocation
rates
• Sequencing of production so as to reduce setup times Internal production scheduler
• Shift rosters that take account of restrictions on working hours
(overtime, work on public holidays)
KPI: key performance indicator
to shift plans based on worker shift rosters and pre- 3. 3
dicted overtime hours and changes to inventory levels. Cell Production Management System
Work is currently underway on extending its use This system is intended to shorten the time it takes
to other sites, including refrigerator production at increasingly diverse new employees to become profi-
the Refrigeration & Heating Home Appliances Unit cient and to raise the level of worker training.
and injection molding facilities at Hitachi Consumer With the structure of the workforce being such
Products (Thailand), Ltd. (HCPT) (see Figure 2). that 70% or more of roles are outsourced, with high
turnover and staff coming from an increasingly diverse
3. 2 range of national origins, shortening the time it takes
Worker Recognition System new employees to become proficient in cell produc-
This system is intended to automate attendance tion tasks that take about 10 minutes per worker,
management and worker assignment. It shares infor- without compromising safety, is a major challenge
mation with a newly implemented attendance man- when seeking to improve efficiency.
agement system to provide better information about This system displays the information that cell work-
attendance and uses information on the skill sets of ers need on a monitor installed directly in front of
individual workers to automatically generate a staff them, providing a wide variety of instructional infor-
reassignment map to deal with any worker absences. mation including images showing how work is to be
Through the sharing of data with employment performed, how to avoid mistakes such as forget-
management systems, it has also rationalized the aux- ting to attach certain parts, and communication (see
iliary tasks of attendance managers, such as collating Figure 3).
overtime details and working through the approvals (1) Better information about working hours and team
process. efficiency
Hitachi Review Vol. 69, No. 1 92–93 93.Figure 3 — Cell Production Management System
The system improves efficiency by interactively linking information on individual cells with the management of all areas of the cell assembly shop.
Cell production management system Work guidance
Overall production management screen for individual cells
Multiskilling
Screen for “digital poka-yoke”
(mistake prevention) system
Parts request screen Bi-directional communication
improvement
Quality
Picking sensor
(work instruction lamp)
To raise awareness among workers and to help For purposes of quality management and maintain-
supervisors provide efficient practical training, the ing efficiency, the system includes functions for using
three-worker cells that are a feature of the production picking sensors to raise an alarm if parts are taken in
of front-loading washing machines are equipped with the incorrect sequence and for requesting someone
displays showing the target and actual work times for to bring more parts.
each worker and the difference between actual and tar-
get. The system also ensures maximum team efficiency 3. 4
by automatically allocating workers in a way that opti- Monitoring Cell
mizes the balance of proficiencies within each team. The production efficiency of an assembly cell for
(2) Communication robotic vacuum cleaners was enhanced by putting
The cell monitor displays information for work- in place a single-worker cell for a monitoring tech-
ers, providing details of the day’s overtime require- nique that combines the processing of images from a
ments and asking them whether or not they can commercially available work assistance camera and a
work overtime. The system improves the efficiency newly developed system. This was done to satisfy the
of work-related communications and keeps track of requirements of a tightly packed design that features
the physical condition of workers by having them the same functions as competing models in half the
use touch-operated switches mounted in the cells to volume, with a high component count and a compli-
respond “Yes” or “No” to these prompts. cated wiring harness (see Figure 4).
(3) Use of visual aids for job training (1) Work guidance system
Workers are able to view visual representations of Based on signals from the camera, the system
safety- and quality-related work instructions, includ- enables work to proceed smoothly without the need
ing the ability to backtrack if they want to review this to operate switches, with functions that include indi-
information. This has made it possible to shorten the cating which tools to use based on the task being
time it takes workers to achieve proficiency. performed and automatically positioning parts where
(4) Avoidance of operator error and parts unavailability they are easy to access.
94.FEATURED ARTICLES
Figure 4 — Monitoring Cell
The figure shows the functions and layout of the monitoring cell. As the worker carries out a task in accordance with instructions on the monitor (A), the
system compares the actual work done (B) with data on how it is meant to be done (C). This prevents problems such as incorrect assembly or parts being
left out by indicating whether or not the work has been done correctly (D).
Work assistance Work instructions Work progress
camera
Electric screwdriver (A) (B)
System monitor
Tools and parts
are moved into
position as
needed as the
work progresses
(C) (D)
Automatic screw
dispenser
Correct way to assemble Assessment of result
(2) Work checking system (3) Work dynamics analysis system
The system uses the camera to compare the prog- This automatically collects data on assembly times
ress of work against the instructions displayed on the for each work cycle. It enables each step to be ana-
monitor, indicating whether or not the work is being lyzed, including the degree of variability in how the
done correctly. This helps prevent incorrect assembly work is done.
or parts being left out.
Figure 5 — Final Inspection IoT System
The figure gives an overview of the final inspection IoT system and its main functions.
Server A temporary serial number is scanned Server
using readers located at each step of the PP base
assembly process and used to link data sub-assembly Labeled with a 2D code
Final inspection
to the product (temporary serial number)
after molding of PP base
Server 1
3 • Recording of final inspection results 2
and measurements
• Recording of manual rework 2D code
4 Cell assembly line
Label attached to
rear of PP base
Linked to serial number : Barcode reader
Recording of assembly cell number
Acceptance inspection
Touch-panel screen
• Model and other details read when product arrives at assembly line (to provide
information on number of incoming products)
• Real-time display of final testing, reworked items, and inspection data
• Details of problems are displayed on cell monitor in real time
→ Rapid response and prevention of recurrence
• Automated collection of quality statistics
• Serial number linked to barcode (to improve traceability)
#
Cell 3 Problem detected!
Leak check 1 Defect statistics
Clip on external drain hose is
out of place
Rework Re-attach clip
Comment
IoT: Internet of Things PP: polypropylene 2D: two dimensional
Hitachi Review Vol. 69, No. 1 94–95 95.3. 5 3. 6
Final Inspection IoT System Equipment Status Management System
This system has been introduced into the appliance The shop where the exterior parts of front-loading
assembly process in a way that treats components washing machines are press-formed is equipped with
manufactured internally and labeled with QR codes* a number of presses and robots, and operates as an
as key parts. It is intended to make quality manage- unmanned production line. The equipment status
ment more transparent, to provide real-time feed- management system acquires timely information about
back, and to rationalize auxiliary tasks. Information the equipment setup and any problems that occur. The
is recorded for each appliance on whether products intention is to shorten the time taken to restart from
pass the post-assembly final inspection as well as a shutdown and to increase equipment utilization and
on things like any rework or adjustments that were production volumes. A system for viewing what is hap-
made. This information is linked to the serial number pening on the line has been put in place by installing a
when acceptance inspection is performed. By doing number of large-screen monitors in the workplace and
so, use of the monitors installed in the assembly cells displaying the layout of the line as a whole, and the
to display feedback about defects in real time when a presses and robots in each unit (see Figure 6).
problem is detected not only enables a quick response
when the same defect recurs, but also improves trace- 3. 7
ability and automates the preparation of daily inspec- Production Real-time Monitoring System
tion reports and quality statistics (see Figure 5). A production real-time monitoring system (PRMS)
* QR code is a registered trademark of Denso Wave Inc. for providing information on all steps along the pro-
duction process that is integrated with the systems
Figure 6 — Equipment Status Management System
Color coding is used to indicate the operating status of each unit. By displaying the die status (whether setup is in progress or complete), time taken for
setup, and the state of interlocks for each area so that whether the equipment gate is open or closed can be seen at a glance from anywhere, this signifi-
cantly improves the performing of safety checks when restarting equipment. It also makes it easier to deal with problems and determine where delays
are happening based on robot control signals such as when robots take hold of a workpiece.
PCM press line
Center panel Press #2
Exterior 1 2 Robot
3 Press #3
(sides)
4 Press #4
Press #1 Flow of materials
6
Lower
panel 5
■ System block diagram
7
Display
Automatic Shutdown or setup
Production operation in progress
Inspection or short halt
Automatic Shutdown or setup
Robot operation in progress
Automatic Shutdown or setup
Press operation in progress
Area safety
Closed Open
gate
Functions
Area 3 Area 2 Area 1 (1) Show progress of die setup (setup time measurement)
Centering mechanism, balance Seamer, Welder, press, flanging (2) Show information on holdups (utilization measurement)
scales, screw tightener, robot #3 robot #2 machine, robot #1 (3) Show status of safety features (interlocks, safety gates, etc.)
PCM: pre-coated metal
96.FEATURED ARTICLES
Figure 7 — Production Real-time Monitoring System
Shows at a glance what is happening in the room and provides a dashboard for centralized management of different systems.
PRMS for front-loading washing machines (Production Realtime Monitoring System)
14:36, Tues. 07/16/2019
Room 4B Room 3B 168 days since last accident
Equipment Running Standby Halted Equipment Inventory (Jan. 1, 2019)
Equipment Forming of Equipment
exterior shell Inventory OK Overstocked Understocked Production
[1.2] [1.0] volumes No.4 No.5
Flange
[ ]: Previous cycle time (min.) Standby: 15 min. or more Halted: 30 min. or more Room 3E
Equipment Equipment Scheduled 515 485
[1.2] sub-assembly [1.0] Equipment Inventory
Exterior shell stocker 2 Exterior shell stocker 1 Produced 279 203
Equipment Inventory Equipment Inventory Room 5E In progress +34 −28
[1.0] [1.2]
Equipment Inventory Utilization (%) 113 87
Forming Drive assembly and testing Drive assembly and testing Prime by
first intent (%) 99 97
Equipment Equipment Equipment Equipment Cycle Target
[0.7] [1.2] [1.2] [3.2] 1.33 1.41
time
(min.) Actual 1.17 1.61
Drum forming Quality
Appliance preliminary assembly [equipment] Overall [1.1]
No. 4 line (SUS) Unaccepted
defects On-site defects
Final Appliance final Equipment
Packing testing assembly 11 10 9 8 7 6 5 4 3 2 1 [0.8]
[−−] [18] [17.9] [8] [5.7] [8.4] [10.9] [10.1] [9.6] [12.8] [−−]
Production volumes
Equipment Equipment Equipment Inventory Staff recognition Lead time
Store [1.0] [1.0] [0.9]
Production
Main aisle status Defective parts
Exterior processing (PCM) Equipment
Equipment Inventory Appliance preliminary assembly [equipment] Overall [1.3]
No. 5 line [1.0] Appliance final Standby or shut down equipment
assembly
Packing Final testing Equipment 10 9 8 7 6 5 4 3 2 1 Equipment operating times
[−−] [10.9] [11.1] [12.2] [−−] [15.2] [9.4] [11.6] [8.2] [8.9]
[1.2]
Equipment Equipment Other
Store [0.4] [1.0]
Noticeboard
[--][10.9][11.1][12.2][--][15.2][9.4][11.6][8.2][8.9]
PRMS: production real-time monitoring system SUS: steel use stainless
mentioned avobe was installed to identify bottlenecks The areas that Hitachi GLS plans to work on in the
across the entire production process and to provide future are the upgrading of its core business systems by
productivity information (prime by first intent and adopting integrated enterprise resource planning (ERP),
plant utilization) (see Figure 7). The same philosophy the efficient allocation of design and manufacturing
was adopted in the installation of a similar system on resources through the enhancement and integration
the refrigerator assembly line at HCPT. The system is of supply chain management (SCM) and engineering
used to make improvements aimed at reducing losses chain management (ECM), and the use of digitalization
by providing information about what is happening on for better quality traceability. By achieving highly effi-
the refrigerator production line. cient workplaces, Hitachi GLS is aiming for the faster
and more accurately targeted supply of value-laden
products that suit the needs of individual consumers.
4. Conclusions
Because the installation of IoT systems makes it pos- Authors
sible to collect data from “things,” data can be shared Nobuhiro Ishida
MONOZUKURI Management Unit, Products Division,
between people, and between people and equipment. Hitachi Global Life Solutions, Inc. Current work and
As anyone can make use of this data, it is possible to research: In charge of Monozukuri management
promotion for Hitach GLS in Japan and abroad.
identify where the problems lie in a workplace, come
up with the best possible solutions in an efficient
manner, and implement improvement actions quickly. Toshiki Ishida
SCM Reform Promotion Center, MONOZUKURI
By facilitating human resource management and Management Unit, Products Division, Hitachi Global
training at manufacturing workplaces, where diversity Life Solutions, Inc. Current work and research: SCM
reform support work.
is on the rise, these IoT systems are an important fac-
tor in enhancing SQDC.
Hitachi Review Vol. 69, No. 1 96–97 97.You can also read
