Thumbs up for ultrasonic record cleaning
@antinn Thank you for your interest in this topic and your contributions. Fwiw, we are talking about units costing more than $2k. At least I am; I don't know what Terry9's machine cost.. I tried the cheap Chinese route and it proved unreliable. If I'm willing to spend a lot more time with a lot more mess, I can get a record as clean with a one-at-a-time horizontal machine and enzymes (eg Loricraft and AIVS) as I can an ultrasonic with filtering. My goals were to maximize throughput, reduce the time needed to spend on cleaning while still obtaining clean records. My setup and technique are designed to meet those goals. Your comments seem largely related to sizing. I'm sure we can agree that issues will occur with a rig improperly sized to do the job that one asks of it. Generalities warrant assessment against specific set-ups. An inherent problem with using ultrasonics to clean PVC is that as a plastic, it is going to absorb ultrasonic energy Everything vibrates and everything absorbs energy. That PVC absorbs energy is not an inherent problem to the use of ultrasonics for cleaning records, at least to the point that whatever "problem" may exist is not a deterrent to its use.. The successful use of ultrasonics for cleaning records - and it can be successful - is demonstration of its efficacy. There is no standard for measuring what counts as clean. There is no effective way to compare techniques or methods. You cannot clean the same record twice. When do you stop cleaning? My rule is: if it sounds clean it is clean. I'm familiar with Fuchs and Zenith and consider them knowledgeable resources. Apart from observing that plastic baskets absorb energy, It is unclear how basket design is relevant in the case of cleaning records which uses no basket. If you overload the UT tank with records, you are going to significant reduce the power available to clean. There are many sized tanks. This statement begs the question. As Fuchs points out tank size, surface area, proximity to transducers, etc. are relevant. So what counts as overloading? This argument simply says a tank is overloaded when there is a significant reduction of power availalbe to clean.. Energy asorbed within the tank is not the energy used to power the transducers whose output is independent of what is absorbed. If the tank and its transducers are insufficient to do the job then there's a sizing problem. It's not like absorbed energy reduces the overall energy in a tank at a given time. Transducers continually cavitate, continually cause the creation of vacuum bubbles for the length of a cycle. Records continually rotate across working transducers. |
@terry9
Okay. Given enough time leaving an object in a constant stream of water will often result in a clean object. Exposed to the milder implosive power of more small bubbles coming off a higher frequecy may remove a substance - given enough time. But I don’t want to think about the composition of the dirt on a record or continually vary the time of a cycle according to that composition. Through trial and error I arrived at 10 minutes at 80kHz and 10 minutes at 37kHz - and that works. Rarely do I need another cycle. Wrt the whole wavelength isse, which I see as largely theoretical, hopefully we’ll just agree to disagree. My dual frequency approach can process 5-6 records in 20 minutes and I’m quite satisfied they are clean. But I’m not a dogmatist, I will try using an extra spacer and 4 records though I’m uncertain how I would gauge results unless there is a significant difference. The use of multiple frequencies within a cycle is common practice for industrial ultrasonic cleaning - I read no articles that talk about wavelength, for example specific item spacing for 40kHz, which is probably the most common frequency used. When f=.037MHz and c=1480m/s (water) Wavelength=40mm My spacing is ~31mm. Thanks for your engagement on this topic. I appreciate your interest. |
@jtimothya, Energy supplied to the transducers is actually very close to the energy in the tank, since thin stainless steel is essentially transparent to ultrasonic energy. If the plastic is easily deformable such as a PVC record, unlike thicker metal, then plastic will absorb energy which will be cause an increase in PVC record temperature, increase in the bath temperature from UT notwithstanding. Overloading for metals used for UT tank cleaning has been a topic of conversation and analysis for some time with fixturing and spacing applied to achieve acceptable results. But for metals (and some non-metallic) cleanliness verification has been in use for decades. For critical applications such as high pressure oxygen were surface contamination levels as low as 5 mg/ft^2 and particles as small as 50 microns (if accelerated by flow) can lead to a fire (that looks like an explosion) NASA and the Navy have very detailed cleanliness verification methods using very specific chemistries and analysis methods - you may find this report of some casual interest - https://p2infohouse.org/ref/14/13872.pdf; I wrote it. I developed the cleaning and verification procedures and I share the patents for Navy Oxygen Cleaner, the details are now formally documented MIL-STD-1330/1622; so I do have 'some' knowledge in this area. However, use of UT to clean PVC records is a relatively new application. But, in the case of PVC records that have a very defined geometry and surface area, overloading can be analyzer by number of records per tank and per watts. But, this can be complicated by UT transducer location - side of tank or bottom. If side of tank, will record(s) in the center of the stack see the same cavitation energy? The record grove is pretty well defined reported as a V-shaped groove that is 56 microns (0.0022") wide at the top, a radius of 6 microns (0.00025") at the bottom, and a nominal depth of 28 microns (0.0011"), with groove spirals are nominally 200 grooves per inch equal to a groove separation of 125 microns (0.005"). Note that since the stylus rides below the record surface, contamination on the surface of the record should have little impact unless it is deep enough to affect the surface the stylus sees, which is why some used records with very fine surface scratches (likely caused by use of multi-stack record changers) can still play perfect. The chemistry used in the UT tank can have a significant impact. The very small grooves of the record really need a cleaning agent/fluid that will reduce water surface tension to assist with wetting/getting into the groove. This is very different from smooth metal surfaces. Tergitol 15-S-9 is a gentle non-ionic surfactant and at 0.06 wt% is at its critical micelle concentration (CMC) and will reduce the surface tension of the water from 72 dynes/cm to 30 dynes/cm, and with a 13.3 hydrophilic-lipophilic balance (HLB) categorizes it as detergent. When using surfactants you target a concentration of 5-10 times the CMC to get acceptable bath life, any more and you only complicate rinsing. If you do not rinse with water (can be simple tap followed by DI water final simple spray rinse), softly adherent contamination may remain and the surfactant will bind to the PVC in an invisible transparent layer (just angstroms thick) that can affect the record sound and 'gunk' will build up on the stylus. Using any aggressive solvent based chemistry or high temperature or too much power and you risk extracting or possibly eroding some of the PVC binders in the groove noting that the groove ridges are much smaller than the groove. What you are trying to clean, has a significant impact, and for most general type cleaning such as a PVC record, a wide variety of contaminants can be present. Depending on the type of contaminant, there will be a minimum exposure time, and in precision cleaning for sensitive material such as PVC a maximum duration of 10 minutes would apply (ref MIL-STD-1330). But, the PVC itself presents a difficult material because particles may be embedded in to the surface. Temperature always helps since the PVC will expand helping to free up embedded invisible particles (as small as 1 micron and less), and simple oils will soften and flow. The human eye assisted with bright white light can see particles sized 50 microns (ref MIL-STD-1330D, I wrote it). So this is not small enough to see the smaller particles that could be in the trough - ~6microns, let alone those between the groove wall ridges. Have you ever tried Ultraviolet (Black) Light to inspect for particles and fingerprints? Blacklight can detect contamination at about 25 mg/ft^2 and particles as small as ~30microns? Animal/vegetable fats will fluoresce. Mineral based oils/greases generally will not fluoresce. But, like you say, there are currently are no cleanliness verification methods for PVC records other than play and listen. So, you are still in the experimentation phase. Otherwise, I do not use a UT tank for record cleaning. I developed my own manual cleaning procedure (that steps off from what the Library of Congress uses) using the VinylStack record protector that I can clean/dry 6 records in about 45 minutes which is good enough for me; and I am fine with the results. I am using a multi-step process of pre-rinse with flowing tap-water, clean/scrub with Tergitol 15-S-9, post-rinse/scrub with flowing tap-water, final rinse with DI water spray, then two step dry - medium-pile lint-free microfiber and final dry with anti-static cloth - after which it only takes another few minutes to completely dry. I developed a fully detailed procedure just for an exercise formatted similar to a Military Standard-Tech Manual. Hoped the above expands upon the knowledge base, and Good Luck. R/Neil |
