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Topic: The best 35mm projector
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Will Kutler
Phenomenal Film Handler
Posts: 1506
From: Tucson, AZ, USA
Registered: Feb 2001
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posted 12-23-2006 08:22 PM
Hi Mark
I would suggest that you open up your copy of "The Machinery's Handbook". Under the chapter "Machine Elements" is an entire section covering "Plain Bearing Materials".
There are 7 key properties of bearing materials:
1: Fatigue resistance
2: Embeddability: the ability of the bearing material to
absorb or embed within itself large or small dirt
particles present in a lubrication system. Poor
Embeddability means that circulating dirt will score
both the bearing and the journal shaft. Good
embeddability means that the bearing material will
entrap this dirt and force it into the bearing material
out f the way where it will do no harm.
3: Compatibility or anti-scoring tendencies
4: Confrmability: malleability and of the bearing material to
conform to the journal shaft during run-in/break-in.
5: High thermal conductivity
6: Corrosion resistance
7: Load capacity or strength
Cast Iron "is an inexpensive bearing material capable of operation at light loads and low speeds, i.e. up to 130 ft/min and and 150 lb/in squared. These bearings must be well lubricated and have a rather large clearance so as to avoid scoring from particles torn from the cast iron that ride between the bearing and journal. A journal hardness of between 150 and 250 Brinell has been found to be best when using cast-iron bearings." In other words, cast iron has poor embeddability and campatibility properties.
Mark, you are also uneducated about oil-lite bearings:
Porous Metals: "self-lubricating bearings are usually made by sintering metals such as plain or leaded bronze, iron, and stainless steel. The sintering produces a spongelike structure capable of absorbing fairly large quantities of oil, usually 10-35 percent of the total volume. These bearings are used where lubrication supply is difficult, inadequate, or infrequent. This type of bearing should be flodded from time to time to resaturate the material. Another use of these porous materials is to meter a small quantity of oil into the bearings such as in a drip feed system." See table 13 for Application limits
So Mark, the reason that oil-lit bearings have failed you is due to improper useage.
Also Mark, your comment regardin Lean Manufacturing makes no sense??? Lean concepts are critical in todays manufacturing world. It all comes down to waste elimination and the optimum utilization of resourcs. Lean is a culture that includes everyone employeed within the manufacturing enterprise.
Regards
Kutler
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Will Kutler
Phenomenal Film Handler
Posts: 1506
From: Tucson, AZ, USA
Registered: Feb 2001
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posted 12-24-2006 11:34 AM
Hi Mark
It seems that you did not read what I wrote. As I said, oillite bushings DO require periodic relubrication.
Also, both Mark and Sam have proven their lack of understanding regarding Lean Manufacturing Concepts.
JIT is much, much more than "bean-counting". JIT is a philosophy based on the planned elimination of non-value added waste from all aspects of manufacturing and on continuous improvement of productivity. It encompasses all activities required to produce the final product, from design to delivery. Besides having only the required inventory when required, JIT also includes quality improvement to zero defects, lead time and queue length reduction, lot size reduction, and the revisement/improvement of manufacturing operations themselves.
JIT has two fundamental objectives: waste elimination and an attitude of continuous improvement (kaizen) In JIT, 7 wastes have been identified:
1: Waste of overproduction
2: Waste of waiting
3: Waste of transportation
4: Waste of processing, itself
5: Waste of stocks
6: Waste of motion
7: Waste of making defective products
Simply put, Lean Manufacturing is about the aggressive elimination of non-value added waste from all aspects of the manufacturing process. And a key part of lean is the use of flexible manufacturing cells. Lean Manufacturing and 6 Sigma complement each other.
The Japanese Lean System has become known as the Toyota Production System. And it is through Lean Concepts that the Japanese were able to kick our (U.S) asses in manufacturing in the post-WWII era. Ironically, Lean is based in large about what Henry Ford wrote in 1926, and resulted in car prices being cut in half and workers wages to double.
An excellent example of a CIM/Lean enterprise is GEMA (Global Engine Manufacturing Alliance). Just type in GEMA in a search engine and a million internet hits will come up. Anyhow, GEMA is a co-op effort of DaimlerChrysler, Hyundai, and Mitsubishi Motors to produce technology-advanced, fuel efficient but powerful, low cost 4-cylinder engines.
Lean has often failed in the United States because it is a work-place culture and philosophy. When people hear "Lean" they think of loosing their jobs. The subsequent result is the sabatoge of Lean implementation. Lean is not about eliminating jobs, it is about eliminating waste.
The history of manufacturing in the US has always been about management vs workers (and how the two always try to screw each-other). Rarly have the two parties worked as a team for the betterment of enterprise.
Key lean manufacturing principles include:
Pull processing: products are pulled from the consumer end, not pushed from the production end
Perfect first-time quality - quest for zero defects, revealing & solving problems at the source
Waste minimization – eliminating all activities that do not add value & safety nets, maximize use of scarce resources (capital, people and land)
Continuous improvement – reducing costs, improving quality, increasing productivity and information sharing
Flexibility – producing different mixes or greater diversity of products quickly, without sacrificing efficiency at lower volumes of production
Building and maintaining a long term relationship with suppliers through collaborative risk sharing, cost sharing and information sharing arrangements.
Lean is basically all about getting the right things, to the right place, at the right time, in the right quantity while minimizing waste and being flexible and open to change. More importantly, all of these concepts have to be understood, appreciated, and embraced by the actual employees who build the products and therefore own the processes. The cultural aspect of lean is just as important as the actual tools or methodologies.
Lean thinking got its name from a 1990’s best seller called "The Machine That Changed the World : The Story of Lean Production". The book chronicles the transitions of automobile manufacturing from craft production to mass production to lean production.
The seminal book "Lean Thinking" by Womack and Jones, introduced five core concepts:
Specify value in the eyes of the customer
Identify the value stream and eliminate waste
Make value flow at the pull of the customer
Involve and empower employees
Continuously improve in the pursuit of perfection.
Cheers
K
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The 35/70mm Combo Is A Nice One As Well...But A Little Big!
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maybe it was you! two other ones went to a struggling small cinema in columbia, they were in dire need of new equipment, and the other one was a P70...the the 35mm/70mm combo that went to some educational institution. I wish I still had them, very very good projectors id trade in a century any day for one of those. The owner of the Prevost company is actually very helpful and awsome to work with, excelent customer support...even if the parts take 30 years to get here... ![[Big Grin]](biggrin.gif)
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