MD_Mechanical Monthly_: The Lowdown on Lead Screws

Please add MD_Mechanical Monthly_ to your Safe Sender list.

May 15, 2009

This month's newsletter looks at some linear-motion devices and includes some expert tips on couplings. There's also video of some tricky helicopter flying that shouldn't be tried at home.

Articles

The Lowdown on Lead Screws
This article compares different lead screws -- roller, ball, and Acme screws -- for linear-motion applications.

Long-lasting linear actuator uses belt drive
A belt-driven linear actuator provides accuracy as well as a long operational life.

Slew Ring Bearings: Gearing up your bearings
This article discusses the advantages of slewing ring bearings, which are sometimes cut with teeth to double as gears. They can be found on cranes and wind turbines, as well as smaller machines.

Getting the most from bellows and elastomeric insert couplings
This video features an expert giving tips on how best to select and use bellows and elastomeric insert couplings. (Run time: 5:57.)

"SMC" COUPLINGS FOR PRECISION POSITIONING

Servometer® SMC Couplings are available with light weight integral clamp hubs for ease of attachment and minimization of marring precision shafts. Servometer® SMC flexible couplings absorb angular and parallel misalignments in combination with axial movements, while precisely transmitting motion and torque. Servometer's stock line of flexible shaft couplings offers torques ranging from 5 in/oz (3.7 Ncm) to 3500 in/oz (2471.8 Ncm). SMC Couplings are low inertia, zero backlash, low wind-up, precision constant velocity universal joints. They also help dampen vibration.

www.servometer.com

Game: Destroy the Castle!
Tired of building useful things? Take a break, brush up on your cannon skills and knowldge of trajectories and destroy that castle!

Film at 11: Helicopter accident at sea
A Greenpeace helicopter nearly slices and dices some deck crew.

New Products

High-speed clutch

The Hi-Mic5 electromagnetic clutch now includes a shaft designed to customer specifications. Two ball bearings in the field assembly and two in the pulley assembly let the clutch handle a 40% higher speed/load than a bushing clutch. The clutch can also take a side load on the pulley, eliminating problems that arise when a timing belt is used. All rotating parts use ball bearings, increasing clutch life over that of bushing-style clutches.
The clutches can come with a lead wire or terminal output. Also available is a custom dust cover to protect the armature against contamination.
The Hi-Mic is recyclable — component parts can be easily disassembled, separating copper from steel from plastic.
More Information:
Ogura Industrial Corp.

Linear-motor-driven actuator

The P3 linear-motor-driven actuator is designed with the linear-motor coil integrated into the top assembly plate for optimized thermal conductivity. This design provides high stiffness/low cogging for extremely smooth constant-velocity motion even at low speeds.
Features and benefits of the actuator include high speed and acceleration — up to 5 m/sec @ 10 g; two encoder options for high resolution and low cost; alternate motor selections for different load requirements; ironless linear motor for zero cogging and smooth motion; integrated cable-handling system; and travel lengths to 1 m.
The system offers two encoder feedback options. The magnetic encoder provides clean quadrature signals for difficult environments from 1 to 5-µm resolution. The optical encoder provides resolution at 0.5 and 0.1-µm resolutions.
More Information:
Schneeberger Inc.

News from MD

Machine Design Video Spotlight

	Membrane Switches for Harsh Environments
	Joseph Schwartz from The Bergquist Co. shows Lee Teschler of Machine Design magazine the advantages of heat-sealed membrane switches over pressure sensitive adhesive (PSA) membrane switches in harsh environments.

Call out for Questions!

3M industrial Adhesives will be interviewing Jack Roush, Co-Owner Roush Fenway Racing and Chris Andrews, Head Engineer Roush Fenway Racing on May 15, 2009. Do you have an engineering question you’d like to ask them? Submit it here. Visit 3M.com/vhb mid June to see the interview.

Check Out the New Machinedesign.com

Our newly redesigned web site still features the best content and information for engineers provided by engineers but with these new great features.

Multiple Path Navigation
Find content your way. Improved site navigation creates multiple ways to find the content you are looking for.

Supercharged Search
The search function has been highly improved and tested to provide the most effective results for engineers.

Highlighted Resources
Looking for CAD drawings? Find them in our CAD Library. Download whitepapers in the Whitepaper Library. Valuable educational content is featured in the eBook section. Check out the latest in editorial and sponsored video in the Video section.

UPCOMING WEBCASTS

Understanding Key Power Transmission Technologies:
Comparing Belt, Chain & Gear Drives for OEM Projects
Sponsored by Rexnord
DATE: May 28th, 2009
TIME: 2:00pm ET/11am PT

OEM design teams are under pressure to juggle technologies with specifications with the outcome always being a great new or improved product. Many of these projects have Power Transmission components at their core and the wrong technology can really hurt the end product.
Dennis Missun and Nick Derus from Rexnord have gathered information about the critical issues that need to be considered when deciding between belt, chain and gear drive technologies for applications requiring 5 lbs – 100 lbs of force.

The course will cover

Torque Density: comparing key rating systems AGMA & ISO
Application considerations: impact of thermals, friction and vibration
Basics of sizing & selection: information to right-size components
Other Project/End Customer Considerations
Live question/answer session with presenters

Click here learn more and to register!

ARCHIVED WEBCASTS AVAILABLE FOR FREE VIEWING

Click Here for a list of archived Machine Design webcasts.