Six Ways to Optimize Your Towline Investment

Six Ways to Optimize Your
Towline Investment
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Closing the Loop on Towline Efficiency
Towline conveyors offer a cost effective alternative to other types of material handling
systems for moving work pieces between operations in manufacturing and assembly
applications. They are a proven technology, simple in design, flexible in application,
rugged and easy to maintain.
In operation, carriers, or carts, are pulled by a chain encased in a track generally configured
in a rectangular or serpentine loop or multiple loops connected by transfers. Process operations are performed along the loop at selected “stalls” or “spurs.”
Locate the stations
in a logical, repetitive
and successive
pattern around the
entire length of
the system
A towline system is made up of a mainline conveyor, a transfer conveyor or a combination
of the two. Towlines can be configured in a variety of paths using loops, transfers, spurs,
stops, and operating modes to meet a wide range of user needs.
Towline conveyor systems can be installed for a low
initial investment. Low operating and maintenance costs
financially justify the installation over time, resulting in
an extremely low total cost of ownership. Yet, as good
a value as these systems represent, there are ways
to further optimize the investment.
1. MAKE THE MOST OF THE PATH
The components of a towline system include straight
and curved track sections, a drive motor, a chain,
and a controller. The modular nature of the system
components makes it possible to expand and/or modify
the towline to meet changing production requirements.
For example, additional mainline loops can be added,
connected by transfer conveyors, to accommodate
expanded operations or to equip an adjacent facility.
Ramps and elevators can be added to an existing
system to extend the overall towline conveyor system
vertically or to production areas that are situated on a
different horizontal elevation than the primary mainline. Spurs, where carts can be diverted
off the mainline for special work, can also be added or modified to meet new requirements.
Accumulation stops, where carts can be loaded or unloaded, for example, can be activated
or deactivated as need requires.
What is important in the system design is to make sure that the towline is fully utilized for
process operations. In other words, to get optimum value from the installed system, avoid
long sections of unproductive track. Rather, locate the stations in a logical, repetitive and
successive pattern around the entire length of the system. For example, if any part of the
loop is used only to return work pieces to the beginning of the process operation, then that
return length of loop is completely underutilized. Make every effort to dedicate every inch
of the towline to positive process operations.
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In refurbishing an existing system or designing a new installation, it is also necessary to plan
ahead for expansion. During construction, it is much easier and less costly to add spurs or
stops in anticipation of process changes or business growth than it is to add them later.
These additional features can be physically or electronically bypassed until required.
2. REDUCE NON-PRODUCTIVE TIME
Keeping non-productive time to a minimum is the key to improving towline efficiency.
One way is to maximize production by using a continuous creeping chain.
Towlines can move work pieces in three different ways:
1.Continuous creeping
2.Indexing via PLC timer or operator release
3.Non-synchronous with operator-released stops
In continuous creeping operation, the chain and carts never stop and the operators work
on the product while the cart passes by at a very slow speed. In either index and dwell or
non-synchronous operation, the chain moves at a high-speed between stations, causing
operators to wait while the product is in motion between stops.
Keeping nonproductive time to
a minimum is key to
improving towline
efficiency
For example, assume 12 minutes of work per station with stations 12’ on center. In
the continuous creeping mode, assume the chain would travel at 1’ per minute so
the operator would complete work in 12 minutes (1 FPM x 12 feet). However, in either
of the other modes, assume a chain speed of 30 FPM (too fast to work on but safe
around operators) for 12 feet and then 12 minutes of work per piece. In this instance,
the total cycle time per station is 24 seconds to index, plus 12 minutes of work time,
equaling 12.4 minutes of total cycle time. While .4 minutes doesn’t sound like much,
it adds up very quickly!
Advantages of Continuous Creeping Towline Operations
Method
Speed (FRM)
Work Cycle (Min’s)
Distance (Ft)
Index Time (Mins)
Continuous Creeping
1
0
12
12
Total Cycle Time (Mins)
12
Indexing
30
12
12
0.4
12.4
Units
Continuous
Creeping
Indexing or
Non Synchronous
% Increase
w/Creeping
Unit
Cost ($)
Additional Volume
($) w/Creeping
Per Hour
5.00
4.84
0.0323
$20,000
$3,226
Per 8-Hour Shift
40.00
38.71
0.0323
$20,000
$25,806
Per Day - 3 Shifts
120.00
116.13
0.0323
$20,000
$77,419
Per Week - 7 days
840.00
812.90
0.0323
$20,000
$541,935
Per Month
3,650.00
3,532.26
0.0323
$20,000
$2,354,839
Per Year
43,800.00
42,387.10
0.0323
$20,000
$28,258,065
Example: One towline customer implemented a continuous creeping installation. The equipment they sold was at
$20,000 per unit. With the increased 3% production capacity, this customer produced an additional 1413 units annually.
This translated into $28,258,065 in additional revenue by changing from an indexing vs. continuous creeping application.
This is beyond the difference between manual and automated towline operations.
SI Systems | www.sihs.com | info@sihs.com | 800-523-9464 | F: 610-250-9677
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The continuous creeping line inherently produces higher volumes than the other operating
modes as it paces the operators without losing any transit time. The volumes become higher
yet when compared with indexing and non-synchronous systems where operators are
allowed to pace the system via operator “complete” or “index hold” push buttons. This can
result in even lower throughput.
3. REAL TIME MONITORING AND MANAGEMENT OF THE SYSTEM
To allow “real time” interaction with the towline system, an Andon system can be custom
designed to monitor identified system events, thereby allowing management to spot bottlenecks and other system/station issues for subsequent corrective actions.
The modular
nature of the
system components
makes it possible
to expand and/or
modify the towline
Through displays and reporting aids, this system notifies management, maintenance and
other workers of a process problem at a specific workstation using a combination of large
illuminated displays and accompanying audio/visual alerts.
Some displays simply indicate the location of problem encountered; others may specifically
indicate the nature of the problem (i.e. “Operator Needs Assistance”). The alert can be
activated manually by the operator using a pull cord or button, or can be activated
automatically by the production equipment itself when it senses an abnormality or
out-of-tolerance condition. The system can include a means to stop production so the
issue can be corrected before advancing to the next workstation, thereby not passing
the problem forward.
Control system upgrades that allow management to track specific towline performance
parameters can also improve line productivity. Conditions such as frequency of stoppage
at individual workstations can be recorded and uploaded to a factory control system for
analysis. From that analysis, corrective action that might include mechanical, process fixes
or operator retraining can be implemented.
4. BOOST LINE PRODUCTIVITY
Towline systems are essentially a means of conveying work pieces or assemblies from
one workstation to the next in a predictable sequence. However, towline systems lend
themselves easily to interface with other operations that improve the overall productivity
of operations.
For example, custom interfaces can be designed for various requirements (i.e. loading,
unloading, etc.) related to “handling” the transported loads. The system can be configured
for automated electronic cart weighing. An ASRS stacker crane interface with P&D (pickup
and delivery) stations can help automate the materials handling process with the towline
able to exchange materials with the automated system. A cart lift-and-store interface will
allow carts to be handled in aisles for putaway and picking functions related to specific
assembly of custom orders.
5. ELIMINATE MAJOR SYSTEM DOWNTIME
Towline systems are known for their robustness, ease of operation and ease of
maintenance. Clearly, a preventative maintenance program that focuses on regular
lubrication, cleaning, and inspection/adjustment will keep the system running smoothly
for years.
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However, a program of anticipatory maintenance can substantially reduce the threat of
system downtime, which can be costly in any type of manufacturing or assembly operation.
For example, if during routine inspection excessive chain wear is detected, first check to
see if the chain is being properly lubricated and being used as specified. Finding and
eliminating the root cause of a potential problem during routine maintenance will
eliminate costly shutdowns later and extend the life of the system.
Chain jamming is the largest single cause of unnecessary downtime. The system can be
designed to virtually eliminate jamming by solutions such as Track-Gap™ that employ two
proactive means of eliminating track jamming. Track-Gap system consists of a void or open
area in the channel, between the chain guard and channel wall and below the towpin. This
designed area helps keep contaminants contained below the towpin and out of the chains
links. This engineered solution makes a large impact on towline performance.
TRACK-GAP JAMLESS SOLUTION
Cover Plate
Towpin
Active Chain
Return Chain
Chain Guard
Chain Guard
Jam-Free Track Void
6. KEEPING EMPLOYEES HEALTHY KEEPS PRODUCTION HEALTHY
Lost time accidents and injuries cost manufacturers millions of dollars each year in medical
claims, production slowdowns and errors caused by inexperienced temporary hires. The
indirect costs of lost time accidents, such as unbudgeted company administrative time,
replacement hiring and training, are estimated to be four times the costs directly associated
with treating injuries.
Improving and enhancing operator interface with the towline system will help reduce the
occurrence of injuries related to excessive bending, pushing, pulling, stretching, reaching,
and lifting. The most effective way to do this is through cart design or reconfiguration.
Carts can be built with self-contained lifts, operated by foot pedals, to raise or lower
fixtured work pieces to an ergonomically appropriate height for the particular operator at
that station. The custom adjustable height reduces the amount of reaching and bending
necessary to perform operations. Some applications automatically raise or lower the work
piece as it enters a workstation, activated by enhanced controls on the towline and cart
that can be set to match the optimum height requirements of each specific operator.
Carts can also be designed with an indexing turntable that allows operators to easily
reach areas of a work piece that may be on the side opposite to the one presented by
the towline.
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Vertical and horizontal work piece adjustments can substantially reduce the incidence of
About SI Systems
repetitive stress injuries and operator fatigue that can affect system throughput and
Since 1960, SI Systems has been the
operator productivity.
leading provider of automated
conveyance and transportation systems
DESIGN FOR SUCCESS
When considering towline system refurbishment, upgrade or new installation, there are
four critical design elements that must be addressed: work piece weight, line speed, the
footprint, and required throughput. Understand your needs and requirements and then
call the leaders in towline installations and technology, SI Systems to help you today.
for manufacturing, assembly, distribution
and warehouses in North America.
Organizations around the world
have relied on SI Systems’ superior
technology, reliability and reputation
for towline systems for a vast array of
industries and applications.
All Lo-Tow® towline systems come with
uniquely engineered and time-tested
features designed to virtually eliminate
jams and downtime while providing a
superior Return on Investment (ROI) and
Internal Rate of Return (IRR).
In fact, SI Systems provides a Rejuvenation
and Refurbishing program for ALL towline
systems (new or old) to help organizations
maximize their towline investment.
Visit www.sihs.com for more information
or better yet, call 610-252-7321, email us
at info@sihs.com with your thoughts,
concept, problem or project. We will
be happy to help you optimize your
organization’s performance.
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SI Systems | www.sihs.com | info@sihs.com | 800-523-9464 | F: 610-250-9677