Most engineers are familiar with traditional wire wound (coiled) springs, but in this webinar attendees will learn about a viable alternative known as “machined springs”. Based on the whitepaper “Choosing between Machined and Wire Wound Springs”, the webinar will review differences between these two types of springs along with the advantages of each and application tips. If you work with torsion or compression/extension springs learn why a spring with a Pure Moment and Resolved Moment can significantly improve your products performance. The subject of preventing rotation when a spring compresses or extends will also be covered.

1. Advanced Design Options for
Custom Springs.

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

3. Moderator Presenter
Paul Heney
Design World
Alex Ek
Helical Products
Company

4. A Webinar based upon the Helical Products
White Paper
Wire Springs
Versus
Machined Springs
A Comparison

5. • Founded in 1958
• Invented Beam Style
Couplings
Shown here

6. Wire-Wound
Springs

7. Wire-Wound
Springs
Machined Springs

8. • 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

9. Wire Wound
Springs
Machined
Springs
Precision
10% yes yes
1% maybe yes
0.1% no maybe

10. Percentage of Compression
based upon Free Length
Wire Wound
Springs
Machined
Springs
10% yes yes
20% yes yes
30% yes yes
40% yes yes
50% yes maybe
60% yes maybe
70% maybe no
80% maybe no
90% no no

11. Feature Section
Wire Wound
Springs
Machined
Springs
Coils
Round yes no
Square yes yes
Rectangular, radial yes yes
Rectangular, radial
with high ratio no yes
Rectangular, longitudinal yes yes
Rectangular, longitudinal
with high ratio yes yes
Slots
Zero width yes
yes, with
special
process
Zero width w/prestress yes no
0.100 inch yes yes
Over 0.250 inch yes maybe
Number
of
coils
1 coil minimum yes yes
20 coils yes yes
50 coils yes maybe

12. • 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.

13. • 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.

14. Wire-Wound Springs
Parts per minute

15. Wire-Wound Springs Machined Springs
Minutes per part

16. Wire-Wound Springs
Parts per dollar

17. Wire-Wound Springs Machined Springs
Dollars per part

18. 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.

19. Wire Springs Machined Springs
Plating Wire Springs with materials
such as zinc and nickel for
corrosion protection is common
practice.
Plating Machined Springs is less
common because obtaining
complete coverage over the edge
corners is more difficult. The use of
CRES, Inconel, and Titanium
materials provides excellent
corrosion protection for most
Machined Spring applications.
Machined Springs made from
aluminum are typically anodized or
coated to prevent corrosion.

20. Production time is the major influence in cost. Cost wise, Wire Wound Spring cost benefits
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 $5 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.

21. 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 working.
Machined springs can be made from any material that can be machined.
Corrosion Resistant Steels
moderate to high strength
17-4PH Stainless Steel
15-5PH Stainless Steel
Carpenter Custom 455
X750 Inconel
MP35N
High Strength Maraging Steel
C-250
C-300
C-350
High strength alloy steel
4340
4340M
Non-Steels
7075-T6 Aluminum (high
strength)
7068-T6511 Aluminum (very
high strength)
38644 Beta C Titanium (very
high strength and corrosion
resistant)
Delrin 100
Ultem 2300

22. 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.

23. Some of the many
Machined Spring
Attachments
available for
Compression and
Extension
Springs

24. Some of the many
Machined Spring
Attachments
available for
Torsion Springs

25. Flexure configurations for
Compression and
Extension Springs that
resist rotation given
axial deformation.
These techniques are
difficult, but not
exclusively unavailable
for wire springs.

26. Triple
Available only in
Machined Springs
Double
Available only in
Machined Springs
Single
Available in both
Wire
and
Machined Springs

27. Single Start Multiple Start

28. Some of the many
Machined Spring
Attachments
available for
Torsion Springs

29. 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

31. 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.

35. Questions?
Paul Heney
Design World
pheney@wtwhmedia.com
Twitter: @DW_Editor
Alex Ek
Helical Products Company
machinedsprings@heli-cal.com

36. Thank You
q This webinar will be available at
designworldonline.com & email
q Tweet with hashtag #DWwebinar
q Connect with Design World
q Discuss this on EngineeringExchange.com