VAC AERO International

Heat Treat Operators: How Well Do You Understand Dry Pumps?

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Source: VAC AERO International Inc.

With the popularity of dry pumps in furnace operations, vacuum furnace operators need to "have a handle" on how to operate them.

In this best of the web feature, the author explains the principles of operation, screw pump design, and various other screw pump characteristics. Learn about the 5 phases of dry pump operation and more in this succinct article.

An excerpt:

"Dry pumps represent a technology that is of interest to many heat treaters as they strive to increase performance and minimize cost and downtime. The advantages of these pumps are comparable to their oil sealed rotary vane cousins, and in certain applications, offer distinct advantages."

Read more at "Dry Pumps: Screw Type"

Heat Treat Operators: How Well Do You Understand Dry Pumps? Read More »

A Brief History: The Rotary Vane Oil Sealed Vacuum Pump

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Source: VAC AERO International Inc.

Vacuum pumps. What are they used for? Specifically, rotary vane oil sealed vacuum pumps. What goes on inside these machines? Where did they come from? If you know what we mean by the “slap-slap” or “clack-clack” noise, can you also list the pros and cons of this feature?

In the words of today’s best of the web, “This article discusses one and two-stage ‘medium vacuum’ oil sealed rotary vane vacuum pumps that can produce a catalog ultimate vacuum of about 1 x 10-2 Torr (0.01 Torr or 10 microns) for a one stage model and about 1 x 10-3 Torr (0.001 Torr or 1 micron) for a two-stage model.”

 

An excerpt:

[blockquote author=”VAC AERO International” style=”1″]The last improvement that the direct drive pump has over the VBD pumps is the ability to use the oil pressure to open and close a valve at the inlet of the pump. In VBD pumps the problem of oil ‘suck back’ into the vacuum system…[/blockquote]

 

Read more at “The Oil Sealed Rotary Vane Vacuum Pump – Background and Designs”

 

 

 

A Brief History: The Rotary Vane Oil Sealed Vacuum Pump Read More »

Vacuum Measurement Units: A Language Explained

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Source: Vacaero.com

 

"Vacuum gauges all measure the pressure readings in the range from atmospheric pressure down to some lower pressure approaching absolute zero pressure, which is not attainable. Some gauges read the complete range and others can only read a portion of the range, usually used for very low pressures."

A typical vacuum furnace can have at least three electronic vacuum gauge heads to monitor the level of vacuum at various positions. These gauges send signals back to the control systems, and "the vacuum readings are used to ensure that the vacuum pumps are working correctly and that the process chamber is at the correct low pressure (vacuum) for the specific process."

In this Heat Treat Today Best of the Web feature, VAC AERO International shares how different vacuum measurement units are being used around the world today.

Read more: Understanding Vacuum Measurement Units

(Photo source: vacaero.com)

Vacuum Measurement Units: A Language Explained Read More »

Cleaning Workpieces: Vacuum Vapor Degreasing

/ FEATURED NEWS, FIXTURE RACKING SYSTEMS TECHNICAL CONTENT, MANUFACTURING HEAT TREAT, MANUFACTURING HEAT TREAT NEWS, PARTS CLEANING NEWS

Source: VAC AERO International

 

In order to maintain the cleanliness of workpieces and baskets or fixtures in the vacuum heat treating or brazing process, it is helpful to establish a pre-treating cleaning practice. Vapor degreasing has emerged as a cleaning process with the acting principle that the solvents will dissolve the contaminants on the workpiece and remove them by dripping off the part. In this week’s Technical Tuesday article, a Best of the Web feature, we bring you an article from VAC AERO International addressing the development of the process, the steps involved in vapor degreasing, and comparisons with other cleaning methods.

Cleaning in a solvent offers a level of simplicity and forgiveness not seen in aqueous methods. At one time, solvent cleaning was considered mandatory for successful vacuum processing but environmental concerns (VOC and other emissions) and improvements to aqueous systems including drying technology has seen the industry shift to aqueous cleaning as the norm. Today, however, with the advent of vacuum technology, vacuum vapor degreasing has emerged as a viable alternative to aqueous processing.”

A preview:

Vacuum vapor degreaser schematic with operational sequence steps. (“Removal of Entrained Moisture from Powdered Metal Parts Using High-Temperature Solvent and Vacuum” PM2TEC 2003, via VAC AERO International)

Main image photo credit/caption: Vacuum Processing Systems LLC (via VAC AERO International) / Typical vacuum vapor degreaser 

Read more: “Vacuum Vapor Degreasing”

Cleaning Workpieces: Vacuum Vapor Degreasing Read More »

Common Sense Guidelines for Loading Parts in Vacuum Furnaces

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Source: VAC AERO International

 

From minuscule medical implants to massive aerospace engine parts, vacuum furnaces process components that come in a variety of shapes and sizes. The challenge that faces a furnace operator is to load parts in such a way as to maximize efficiency (important) but also achieve desired metallurgical properties and minimize distortion (more important).

Understanding that loading options generally follow common sense rules can help with the puzzle of load arrangements, spacing parts properly, accommodating geometric irregularities, and loading orientation. This Technical Tuesday feature examines everything to consider about loading parts into a vacuum furnace — from the size and orientation of a workload to the “final spacing . . . [as] dictated by concerns for heating, soaking, flow (of partial pressure or backfill gases), the type and volume of quench media (e.g. oil, gas) and gross load weight.”

 

Table 1 – Common Furnace Workload Sizes

Table 2 – Typical Part Spacing Requirements

 

 

Read more: “Loading of Parts in Vacuum Furnaces”

Photo credit/caption: Vac Aero International / Typical Vertical Furnace Loading Configuration

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The Heart of a Vacuum Furnace System

/ FEATURED NEWS, MANUFACTURING HEAT TREAT, MANUFACTURING HEAT TREAT NEWS, VACUUM PUMPS GAUGES VALVES, VACUUM PUMPS GAUGES VALVES TECHNICAL CONTENT

 

Source: VAC AERO International

 

Heat treaters know that the heart of a vacuum furnace system is the pumping system. As broad as the variety of furnaces is, so is the selection of pump types.

A roots blower, which also goes by the name “booster pump” and “intermediate stage vacuum pump,” is a dry, gas transfer pump that boosts the performance of the primary pump, providing an increase in pumping speed and pressure. This article from VAC AERO International’s Vacuum Pump Technology: Education and Training page provides an exhaustive analysis of the heart of a vacuum furnace system: the pump.

“Roots blowers have the reputation of being virtually indestructible and run for years seemingly unattended while the primary (mechanical) and high vacuum (diffusion pumps seem to receive all the attention. While they need little day-to-day maintenance, monitoring of the oil level in the pump is required. The main function of these booster pumps is to improve pump-down rates and ultimate vacuum levels.” ~ VAC AERO International

Read more: “Roots Blowers (aka Booster Pumps)”

The Heart of a Vacuum Furnace System Read More »

Selecting the Right Vacuum Pump Oil Starts with Knowing Your Pump

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Source: VAC AERO International

 

Vacuum furnace heat treaters know that one of the most critical parts of their system is the pump oil, but it may be a bit overwhelming trying to determine which is the right kind of oil is needed. Selecting the correct vacuum pump oil starts with knowing your pump.

“‘Oil’ is a bit of a misnomer because modern pump oil technology has evolved well beyond the original distilled petroleum products. There are now double- and triple-distilled oils available, as well as hydro-treated oils, low sulfur oils, silicone-based synthetic oils, and flushing oils used to clean the pump. Due to the wide variety of formulations available, these are often now referred to as pump ‘fluids’ rather than pump ‘oils’.” — VAC AERO International

“Different pump oil formulations are specifically designed for different pumps and different vacuum applications,” notes VAC AERO, and a key factor in learning how to select the correct pump oil is the understanding of vapor pressure, viscosity, and distillation methods, as well as solvent refining, hydrotreating, synthetic oil (Perfluoropolyether), flushing oil for vacuum pumps, and diffusion pump oils.

 

 

Figure 1 | Viscosities of various liquids

 

Read more: “Vacuum Pump Oil”

 

 

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A Heat Treater’s Primer on Getter Materials

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Source: VAC AERO International

 

A common dilemma for operators of vacuum systems is to protect the integrity and maintain the life expectancy of components when the presence of unwanted gaseous contaminates threatens to destroy the sensitive materials in the processing environment. Getter materials are the MVPs that step up to the plate to protect work in a low-pressure vacuum environment.

Table 1 [1] Getter Capacity of Common Materials
The folks at VAC AERO International have provided a primer on getter materials which answers the heat treater’s questions, such as:

  • What is a getter?
  • What are the properties of getter materials?
  • What materials are best as getters for most heat-treating applications? What about for more sophisticated applications?
  • What are non-evaporative getters, and what role do they play?

“For heat treaters, getters are often considered a last resort to help keep parts ‘bright and clean’. In point of fact, they play an important role in successful vacuum processing of many highly sophisticated products and materials. As a result, we need to do a better job of understanding their role; how and where they can help.”

 

Photo Credit and caption: Titanium Discs used as a Getter Material in Brazing of Oxidation Sensitive Components – (Photograph Courtesy of California Brazing, Newark, CA)

A Heat Treater’s Primer on Getter Materials Read More »

Matching Gases with Vacuum Heat Treatment Operations

/ BULK GASES & SYSTEMS TECHNICAL CONTENT, FEATURED NEWS, MANUFACTURING HEAT TREAT, MANUFACTURING HEAT TREAT NEWS, VACUUM FURNACES TECHNICAL CONTENT, VACUUM PUMPS GAUGES VALVES TECHNICAL CONTENT

 

Source: VAC AERO International

 

Relative Gas Supply Cost Notes: [a] Based on a minimum usage of 2830 cubic meters (100,000 cubic feet) per month. [b] All gases compared to nitrogen whose relative cost is unity. [c] Based on liquid supply.
Heat treaters use a variety of gases with vacuum furnaces during the processing cycle in partial pressure operation, for backfilling to atmospheric pressure at the end of the processing cycle, and for cooling/quenching. In this article, VAC AERO describes the most common of these gases — (in order of frequency of use) nitrogen, argon, hydrogen and helium — as well as other common gases such as various hydrocarbons and ammonia (for vacuum carburizing/carbonitriding) and specialty gases such as neon (for certain electronics applications), and analyzes their uses and value in various vacuum heat treating processes. In addition, their relative cost per 100,000 cubic feet, the liquid properties and physical properties of common backfill gases, and the conversion between common pressure and vacuum units are explored.

Read more: “Types of Backfill, Partial Pressure, and Cooling Gases for Vacuum Heat Treatment”

 

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