FAQ
Frequently Asked Questions
These answers are based on questions we have actually received from customers. If your question is not covered here, please feel free to contact us.
Q. Is this an electropolished (EP)-grade finish?
A. We use chemical polishing (CP), not electropolishing (EP). The difference between the two is not one of grade — they are fundamentally different processes. Ultra-fine bores of Ø0.2 mm and bellows interiors physically cannot be electropolished, because an electrode cannot be inserted. For these geometries, chemical polishing — which works by bringing the chemistry into contact with the surface — is the practical option. Beyond smoothing, chemical polishing also improves the surface chemistry itself, such as raising the Cr/Fe ratio.
Q. Do you have third-party measurement data?
A. Yes. Our chemical polishing process has a measurement track record of surface chemical analysis (Cr/Fe ratio, oxide layer thickness, etc.) conducted by RJ Lee Group (USA) in accordance with SEMI standards (reference data measured on a different product and material). Laboratories capable of accurate surface chemical analysis are limited worldwide, and we use third-party measurement data as our benchmark. Measurement of the current capillary product by RJ Lee Group or an equivalent laboratory is planned.
Q. What internal surface roughness (Ra) do you achieve?
A. Ra 0.17 µm on the current capillary product (0.2 mm ID, SUS316L), measured by laser microscope. Note that Ra is a metric mechanical polishing can also reach to a certain level, and it does not represent the whole of internal surface quality. In flow meters, sensors and semiconductor fluid lines, it is the chemical state of the surface — the Cr/Fe ratio, cleanliness, and freedom from residual stress — that governs component life and performance. We recommend starting the conversation from the internal surface quality your application actually requires.
Q. Can you finish below Ra 0.05 µm?
A. The practical lower limit for chemical polishing is around Ra 0.1 µm. That said, applications that genuinely require Ra 0.05 µm or below are rare. In most flow meter, sensor and semiconductor fluid-line applications, it is the chemical quality of the internal surface — Cr/Fe ratio, cleanliness, freedom from stress — rather than the absolute Ra value that determines performance. Rather than asking “how low can Ra go,” we suggest starting from “what internal surface quality does this application need” — and we will propose the most suitable specification.
Q. Are the Cr/Fe ratio and oxide layer compliant with SEMI standards?
A. Our chemical polishing process has been verified in third-party measurements conducted per SEMI standards, confirming a raised Cr/Fe ratio and the formation of a chromium-enriched oxide layer (reference data on a different product and material). One important point: the final figures for surface chemical quality depend on both the polishing process and the base material. Chemical polishing greatly improves the surface condition, but it cannot exceed the ceiling set by the base material. For products made from our own supplied material, we guarantee specification figures. For toll processing of customer-supplied material, we assure the improvement delivered by the process, and final figures are discussed according to the base material.
Q. What dimensional tolerances can you hold?
A. ID and OD tolerances depend on the base tubing specification and the processing conditions. In flow meter and sensor applications, ID tolerance directly affects measurement accuracy — send us a drawing and we will confirm feasibility and the achievable tolerance range. Please feel free to consult us.
Q. What are the minimum lot size and lead time?
A. Both vary with the specification (ID, length, finishing grade) and quantity, so we quote individually. Our chemical polishing runs on independently developed dedicated equipment suited to volume production, enabling stable supply of large lots. From prototypes through volume production, please consult us according to your quantity.
Q. Can you process customer-supplied material?
A. Yes. We accept toll (contract) internal chemical polishing of customer-supplied material. In this case, we assure the improvement in internal surface quality delivered by the process; final figures such as the Cr/Fe ratio depend on base-material quality and are discussed accordingly. Geometries that are difficult for mechanical polishing or electropolishing — such as bellows — are also welcome.
Can’t find your question here?
Feasibility checks, specification questions — please contact us with a drawing attached. Questions we receive are added to this page over time.