Benefits of Direct Drive Technology
ELECTROMATE
INDUSTRIAL SALES LTD.
Precision Technology & Quality
PC-Based
1-Axis
Standalone
Screws
Motors
Feedbac
k
Speed
Rotary To
Torque
Linear
Matching Conversion
Couplings
Multi-Axis
Standalone
Motor
Bearings
PLC-Based
Amp
Gearboxes
Operator
Interface &
Architecture Machine
Motion Control
Path Gen Position Velocity Torque
Control
Connecting
the Load
Putting the Best Solution Together
Why Direct Drive Technology?
• Direct coupling of the load to the motor
• No compliance between motor and load
• Inertia mismatch is irrelevant (theoretically)
• 1000:1 inertia mismatch applications in place
(standard servo is 10:1)
DDR Direct Drive Rotary Formats
DDR Product
Formats
Ease of Use
Frameless DDR
(Parts set)
Significant integration,
best package fit
Cartridge DDR™
Easy to integrate,
package size fixed
Fully housed
DDR
Easy to integrate,
package size fixed
Frameless - Brushed
• Permanent magnet stator (stationary)
• Wound armature/rotor (rotating)
• Self-commutating
• Limited peak power due
to mechanical
switching that results in
excessive sparking in
DC motors.
• Least torque ripple of
any motor design
Frameless - Brushless
• Wound stator (stationary)
• Permanent magnet armature/rotor (rotating - reduced inertia)
• Commutation is done based on rotor position such that
synchronism is always maintained. This is referred to as selfsynchronism. The motor maintains the ability to deliver torque
regardless of the velocity error.
• High commutation frequencies = high speeds
• Good heat dissipation because the windings are on the outside
• The ability to deliver current based on demand is a key feature of
servos. If the motor is at rest and there is no load, no current is
consumed, and the motor can cool.
• High bus voltage to force current into the windings is available;
mitigates the electrical time constant of the winding
DDR: Direct Drive Rotary
GOLDLINE DDR Features
• Housed motor with bearings
and integrated feedback
• Resolver or sine encoder
feedback
• Single or double bearing
version
• Large thru bore
Typical application:
• Rotary indexing table
•
To replace any mechanical
transmission that is high
maintenance or has short life.
The Benefits of DDR Technology
To gain Benefits of Eliminating Mechanical Transmissions
• Zero maintenance
– No Belts or gears
• Reliability
– Reduce down time
– No transmission parts to
break
• Improved performance
– Increase accuracy up to
50 times
– Eliminate resonance
and oscillation problems
• Clean mechanical
assembly
– Lower parts count
– Reduce assembly
time
• Smooth and quiet
• Hollow shaft option
– Run process thru the
motor
Lifetime Cost – DDR vs. Mechanical
Lower
Throughput
Unscheduled
Downtime
Belt/gearbox
replacements
Belt/gearbox
maintenance
Purchase Price
(all components)
Purchase Price
Cartridge DDR
Cartridge DDR Product Line
• Best features of a frameless DDR
and a fully housed DDR
• Direct drive servo performance &
zero maintenance, in an easy to
integrate package
• It has no bearings…but it has
everything else
• Feedback is pre-mounted and prealignedat the factory
• Single part number ready to mount
•
Eliminates significant
engineering design
through advanced
mechanical design
Cartridge DDR: Section
RINGFEDER
Small Frame Cartridge DDR
Small Frame vs Large Frame
CDDR Application Considerations
•
•
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•
•
Machine has existing bearings?
Through-bore required?
Fast, accurate motion is required?
Reliability and zero motor maintenance is a must?
Fast machine maintenance a requirement?
• Consider ...
–
–
–
–
Axial shaft movement
Shaft dimensions and TIR
Perpendicularity of mounting surface
Thermal capacity of machine structure
Cartridge DDR Applications
• Any application where the machine has its own set of
bearings, but still can benefit from the DDR performance
advantages
• Converting:
– Rollers, Coaters, Feeders, Die Cutters
• Other application examples
– Injection molding: IM machine mold indexing
– Press feed: Incremental motion
DDR Videos
GOLDLine DDR Indexer
Customer Load Wheel
4 Feet Diameter
250 Pounds
S620 Drive Amplifier
240 or 480 Vac
20 A Continuous, 40 Peak
96 Steel pegs
3.75 degrees per peg
Total Inertia 15 lb-ft-s2
DH143M Goldline DDR
250 Lb-ft Continuous
989 Lb-ft Peak
Single Peg Index Velocity Profile
3.75 Degree Move)
Total Move Time 97 ms
Settling Time 13 ms
Velocity Profile
Indexing a Single Peg
If the Video does not play:
• Right click inside Windows Media Player screen above and choose Properties
• Choose “SinglePeg WindowsMediaPlayer” from pull down and “Alphabetic” tab
• Click on button at the end of “(Custom)” row and “Browse” to file on CD-ROM
• File name is “DDR One Peg Index.wmv”, click Slide Show icon to view
One Revolution Index
If the Video does not play:
• Right click inside Windows Media Player screen and choose Properties
• Choose “FullRevolution WindowsMediaPlayer” from pull down and “Alphabetic” tab
• Click on button at the end of “(Custom)” row and Browse to file location on CD-ROM
• File name is “DDR One Revolution Index.wmv”, click Slide Show icon to view
Repeatability Test
Bar Clamped to Table
26 inch radius from
center
Indicator
1 Thousandth Inch / Number
1 Ten Thousandth Inch / division
0.8 Arc Seconds / division
Repeatability Test Video
If the Video does not play:
• Right click inside Windows Media Player screen above and choose Properties
• Choose “Repeatability WindowsMediaPlayer” from pull down and “Alphabetic” tab
• Click on button at the end of “(Custom)” row and “Browse” to file on CD-ROM
• File name is “DDR Repeatability Test.wmv”, click Slide Show icon to view
DDR vs. Mechanical Indexer
Customer identified these advantages of the DDR over the
mechanical indexer they used previously
– Improved Repeatability
– DDR Accuracy and Repeatability do not degrade over
time as with the mechanical indexer
– Can immediately stop DDR motion if there is a process
error
– Greatly reduced audible noise
– Easily change DDR index angle, speed, and dwell
– DDR provides better overall value
Direct Drive Linear
Linear vs. Standard Rotary Motors
Linear motor - rotary motor rolled out flat!
stator
windings
moving coil
N
S
air gap
magnets
Rotating rotor
magnetic way
Comparative Technologies
Mechanical Transmission
Advantages
Disadvantages
Timing Belt
Speed
Compliance, Accuracy
Wear, Contamination
Maintenance
Rack and Pinion
Speed
Backlash, Wear
Long Travel Audible
Contamination
Ball Screw
High Force
Limited Speed
Settling Time
Wear, Maintenance
Indicators for a Linear Motor Solution
•
•
•
•
•
•
•
•
High Speeds
- 200 in/sec (10 m/sec)
High Acceleration - 3-5 g's are typical
Fast Move and Settle
High Resolution
Long travel distances - 20 feet or more possible
Smoothness (zero cogging)
No maintenance (non-contact)
Zero backlash
• High dynamic stiffness, no compliance
Comparison of DDL Motors
Iron Core
–
–
–
–
Ironless
–
–
–
–
–
zero cogging
zero attractive force
ultra-high acceleration
very smooth motion
Up to 1600 N peak force
high peak force
patented anti-cogging design
high force density
Up to 15000 N peak force