This webinar addresses the high points of the original Choosing Between Machined and Wire Wound Springs webinar, and then goes into more detail regarding the unique differences that can significantly affect design considerations. In particular, issues regarding coil and slot geometries plus length limitations will be discussed. The topic of Multiple Starts and why these are becoming more important in many modern spring applications will be viewed from both the performance and cost vantage points. Torsion springs will be revisited with examples of moment computations. The discussion will conclude with examples of springs in dynamic, resonant usage. Attended this webinar to learn: • Differences in spring coil geometries revealed • Design considerations: differences of machined springs vs wire wound springs • Insights into torsional spring attachments • Single Degree of Freedom spring-mass functioning system

1. Endless Possibilities:
Understanding the Expanding World of
Machined Springs

2. Before We Start
 This webinar will be available afterwards at
designworldonline.com & email
 Q&A at the end of the presentation
 Hashtag for this webinar: #DWwebinar

3. Moderator
Presenter
Miles Budimir
Gary Boehm
Design World
Helical

4. Understanding the
Expanding World of
Machined Springs
© 2013 Helical Products Co, Inc.
4

5. A Webinar based upon the Helical White Paper
Wire Springs versus Machined Springs,
A Comparison
Authored by
Gary L Boehm PE
Helical Products Co Inc, Santa Maria, CA
© 2013 Helical Products Co, Inc.
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6. • Founded in 1958
• Invented Beam Style
Couplings
Shown here
© 2013 Helical Products Co, Inc.
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7. Springs
Wire-Wound
Springs
© 2013 Helical Products
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8. Springs
Wire-Wound
Springs
Machined Springs
© 2013 Helical Products Co, Inc.
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9. • Wire Springs existed before the
Industrial Revolution
• First Machined Springs in 1960’s
• Now- New designs created daily
• Both are manufactured with
CNC controlled machines
© 2013 Helical Products Co, Inc.
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10. Wire Wound
Machined
Springs
Springs
yes
yes
1%
maybe
yes
0.1%
no
maybe
10%
Precision
© 2013 Helical Products Co, Inc.
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11. Wire Wound Springs are typically made from medium and high strength steels, nickel alloys, titanium
and stainless steels that gain their strength predominately from heat treating and cold reduction.
CRES (Corrosion Resistant Steels), moderate to high strength
a
17-4PH per AMS 5643
b
15-5PH per AMS 5659
c
CC455 per AMS5617
d
X750 Inconel per AMS 5667 and 5670
Very high strength steel
a
C300 per AMS6514
Other materials of interest
a
7075-T6 Aluminum (high strength)
b
7068-T6511 Aluminum (very high strength)
c
38644 Beta C Titanium (very high strength and corrosion resistant)
d
Delrin 100 (machinable plastic)
e
Ultem 2300 (machinable plastic)
© 2013 Helical Products Co, Inc.
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12. A long, torsion Machined
Spring using a dime for size
comparison.
Wire Springs can be larger.
A small, compression
Machined Spring.
Wire Springs can be
smaller.
© 2013 Helical Products Co, Inc.
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13. Some of the many
Machined Spring
Attachments
available for
Compression and
Extension
Springs
© 2013 Helical Products Co, Inc.
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14. Feature
Coils
Section
Round
Square
Rectangular, radial
Rectangular, radial
with high ratio
Rectangular, longitudinal
Rectangular, longitudinal
with high ratio
Wire Wound
Springs
yes
yes
yes
Machined
Springs
no
yes
yes
no
yes
yes
yes
yes
yes
Zero width
Slots
Number
of
coils
yes
Zero width w/prestress
0.100 inch
Over 0.250 inch
1 coil minimum
20 coils
50 coils
yes
yes
yes
yes
yes
yes
© 2013 Helical Products Co, Inc.
yes, with
special
process
no
yes
maybe
yes
yes
maybe
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15. Percentage of
Compression
based upon Free Length
Wire
Wound
Springs
Machined
Springs
10%
20%
30%
40%
50%
60%
70%
80%
90%
yes
yes
yes
yes
yes
yes
maybe
yes
yes
yes
yes
maybe
maybe
no
© 2013 Helical Products Co, Inc.
maybe
no
no
no
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16. •
In a closed-ground wire compression spring, the active coil (that in
which strain energy can be stored) extends to the very end of the
spring.
© 2013 Helical Products Co, Inc.
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17. • In a Machined, Compression Spring, the active spring coil stops
short of the spring end relegating at each end one slot width and
one structural width unavailable for storing energy.
© 2013 Helical Products Co, Inc.
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18. Production time is the major influence in cost. Cost wise, Wire Wound Springs benefit
greatly from short production times. Machined Springs cannot approach the low cost of
wire product. It would be very surprising to find a very simple and inexpensive Machined
Spring, produced in high quantities costing less than $1 USD each.
•
•
•
•
•
•
•
However, these value enhancements related to Machined Springs usage helps to validate
their usage:
Integrated attachments
Enhanced performance or functionality
Via Multiple Starts, more uniform elastic reactions, and better control of internal moments
Higher precision
Reduced assembly and acquisition efforts
No sound creation from coil contacts
No debris created by coil contacts
Without one or more of these benefits being present, there is usually little justification of
employing Machined Springs in place of Wire Springs.
© 2013 Helical Products Co, Inc.
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19. Wire Springs
Machined Springs
Wire Springs are often shot peened for
enhanced fatigue resistance. This
process is possible because the gap
between the coils is typically wide
enough to permit passage of shot that
can condition the inside of the
opposite coil, as well as the outside of
the coils.
Machined Springs typically have coil
slots that are too small for the passage
of shot. Hence, shot peening is not
common. To insure fatigue resistance,
features such as stress relief holes and
slots can be added to the slot ends.
Selecting high strength, fatigue
resistant, materials is also a significant
benefit.
© 2013 Helical Products Co, Inc.
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20. Wire Springs
Machined Springs
It is not uncommon to plate Wire
Springs with materials such as zinc
and nickel for corrosion protection.
Plating Machined Springs is
uncommon because of the existence of
sharp edge corners that typically
receive insufficient coverage. The use
of CRES and titanium materials
provides excellent corrosion
protection for most Machined Spring
applications.
Machined Springs made form
aluminum are typically anodized or
coated to prevent corrosion.
© 2013 Helical Products Co, Inc.
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21. Flexure configurations for
Compression and
Extension Springs that
resist rotation given
axial deformation.
These techniques are
difficult, but not
exclusively unavailable
for wire springs.
© 2013 Helical Products Co, Inc.
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22. Triple
Available only in
Machined Springs
Single
Double
Available in both
Wire
and
Machined Springs
Available only in
Machined Springs
© 2013 Helical Products Co, Inc.
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23. Single Start
© 2013 Helical Products Co, Inc.
Multiple Start
23

24. © 2013 Helical Products Co, Inc.
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25. Some of the many
Machined Spring
Attachments
available for
Torsion Springs
© 2013 Helical Products Co, Inc.
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26. Attachment
Type
Wire
Spring
Machined
Spring
Tang (Radial)
External and Internal
yes*
yes*
Dual Tang (Radial)
External and Internal
no
yes**
Tang (Axial)
External and Internal
yes*
yes*
Dual Tang (Axial)
External and Internal
no
yes**
Dual Pin Holes (Axial)
no
yes**
Geometric ID Shapes
(square, hex, etc)
no
yes**
*Force at distance requiring force resolution
**Pure moment drive
© 2013 Helical Products Co, Inc.
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27. Multiple Start Machined Springs have a
history of providing effective Single
Degree of Freedom elastic elements
for such systems.
Double Start Springs set the baseline
for such usage, but Triple Start
Springs are the gold standard
because of their uniform stiffness in
all lateral directions.
© 2013 Helical Products Co, Inc.
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28. www.heli-cal.com
© 2013 Helical Products Co, Inc.
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29. Thank you for sharing your time with us…
And now…
Does anyone have a question?
© 2013 Helical Products Co, Inc.
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30. Questions?
Design World
Miles Budimir
mbudimir@wtwhmedia.com
Phone: 440.234.4531
Twitter: @DW_Motion
Helical
Gary Boehm
machinedsprings@heli-cal.com
Phone: 805.928.3851
Twitter: @HelicalProducts

31. Thank You
 This webinar will be available at designworldonline.com & email
 Tweet with hashtag #DWwebinar
 Connect with
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