Ningbo Kent Bearing Co., Ltd

  Are domestic bearings truly inferior to imported bearings? With more than 20 years of experience running a bearing factory, I can tell you the reality is far more complicated than you think.   Why is there seemingly no solution for domestic general-purpose bearings? Technology is not the issue. We have successfully manufactured main bearings for national heavy equipment, so technical capability has long ceased to be an obstacle. Neither is management to blame. Staff at every link follow regulations and perform their duties properly, and there is no widespread dereliction of duty. We are trapped in a systemic deadlock: the entire industrial chain has formed a closed-loop logic of self-preservation. Every department only makes risk-free decisions for its own interests, resulting in local optimization yet a total collapse of overall benefits.   Let us analyze the dilemma of bearing manufacturers first. High-end bearings made from electroslag remelting steel with P4/P5 precision require customized bulk orders with high minimum order quantities, and no party will cover the inventory risks brought by individual high-end batch production. For scattered orders and urgent spot orders, manufacturers adopt ordinary refined steel, simplified heat treatment and basic P0 precision; low-spec products sold in large volumes at thin profit margins guarantee steady cash flow. High-end customized orders are scarce and high-risk, driving many manufacturers to voluntarily launch tiered product supply strategies. From the perspective of motor manufacturers, the lowest-bid bidding system and audit assessment restrict procurement choices. Auditors only compare prices for products with identical models and appearance parameters, and do not recognize implicit quality premiums. Procurement managers who select more expensive bearings will face audit accountability, leaving them no choice but to pick the cheapest qualified suppliers.   Leading foreign brands such as SKF and Schaeffler offer no low-end budget product lines, and uniformly enforce strict standards for raw materials, machining and heat treatment across all specifications. Their decades-long brand barriers, paired with global mass production, greatly amortize high-end manufacturing costs, eliminating the need to cut corners to secure orders. They never adopt a dual-quality strategy with premium batches and budget batches.   The end result is the well-known phenomenon of bad money driving out good money. Domestic general-purpose bearings have long been labeled as short-lived and unstable. Imported brands become the default choice for high-reliability working conditions. Although breakthroughs have been achieved in high-end special bearing technologies, domestic standard general bearings keep losing mainstream market share.   In the next article, we will discuss how to break the deadlock of poor public reputation surrounding domestic general-purpose bearings.        

Motor Bearing Selection: How Critical Is Load Calculation, Really? When selecting bearings, many motor manufacturers prioritize speed ratings and bore dimensions — yet consistently underestimate the decisive impact of load. A bearing's dynamic load rating directly determines the maximum combined load it can withstand, and the L10 theoretical life formula captures this relationship most clearly: bearing life is roughly inversely proportional to the cube of the applied load. Consider the numbers: the exact same bearing set can deliver 30,000 to 40,000 hours under light load conditions. But once it operates continuously near its rated load, service life collapses — raceway fatigue spalling can appear within just a few thousand hours. This is not manufacturing variance; it is fundamental physics. Three Load Types Every Motor Bearing Must Handle Motor bearings do not face radial loads alone. They endure a combination of radial, axial, and impact loads — each demanding careful evaluation. # Load Type Common Sources Consequence of Underestimation 1 Radial Load Belt pulleys, gears, eccentric rotors — the primary load in small and medium motors Excessive radial load causes raceway pitting and spalling; vibration progressively intensifies 2 Axial Load Fans, pumps, motors with significant axial float Standard deep groove ball bearings have limited axial capacity; excessive axial load demands angular contact bearings. Ignoring axial load leads to one-sided wear, abnormal noise, and overheating 3 Impact / Alternating Load Power tools, frequently started equipment with fluctuating loads Steady-state average load alone is insufficient for selection — a larger safety factor is essential, or alternating stress will accelerate fatigue damage Two Common Selection Pitfalls Pitfall 1 — Matching Bore Diameter Only: a standard bearing is selected based solely on shaft size, with zero load verification. The motor runs perfectly during no-load testing. But under real operating load, bearings fail with abnormal noise within a few hundred hours. Repeated replacements yield the same result — because the root cause was never addressed. Pitfall 2 — Oversizing "Just to Be Safe": selecting the highest load rating and largest bearing available, assuming more capacity is always better. Larger bearings bring increased mass, higher friction, elevated motor temperatures, greater energy consumption, and degraded NVH (noise, vibration, harshness) performance. The result is performance overkill paired with unnecessary cost. The Right Approach Effective bearing selection requires calculating actual combined loads — radial, axial, and dynamic — and matching them to the bearing's rated capacity with an appropriate safety factor tailored to the specific operating conditions. No single parameter can substitute for this analysis. About Kent Bearings With over 20 years of deep expertise in the bearing industry, Kent Bearings has developed distinctive product advantages through sustained investment in core technology. Compared to competitors, Kent products not only meet the stringent bearing requirements of diverse industries, but consistently address the most fundamental customer demand: bearing longevity.  

Many engineers, purchasers and equipment managers always have one lingering question in mind: how long can a bearing last under normal service conditions?   Many people hold misconceptions about bearing service life; a bearing is not considered failed only when it seizes up. In engineering applications, bearing failures fall into two categories: 1.Complete Failure The bearing seizes up and cannot rotate, completely losing its service function. 2.Performance Failure (Most Common) The bearing can still rotate, yet it suffers excessive vibration, increased noise, abnormal temperature rise and reduced precision, failing to meet the equipment’s design specifications.   The universally accepted industry judging criterion is clear: the theoretical service life of a bearing expires once the first fatigue spall emerges on its raceway or rolling element. However, actual on-site working conditions differ drastically from theoretical assumptions. Minor initial spalling on many bearings is barely detectable by naked eyes or monitoring instruments, and the bearings can still operate normally. Replacement is only mandated at a later stage when excessive vibration and abnormal temperature rise occur. Therefore, the usable lifespan of a bearing primarily depends on which replacement standard you adopt: High-precision equipment: Replace bearings at the first sign of initial fatigue spalling; General-purpose equipment: Replace bearings when vibration and temperature exceed limits; Rough-duty equipment: Keep running until bearing seizure. Setting aside complex calculation formulas, below are general industry reference values compiled in accordance with mechanical design handbooks and universal design standards from bearing manufacturers:   The standard design service life for bearings in ordinary small & medium industrial motors ranges from 20,000 to 40,000 operating hours. This serves as the universal benchmark for equipment type selection, structural design and quality verification. It must be emphasized that this figure is a design value under standard operating conditions, applicable to regular loads, rated rotational speeds, sufficient lubrication and clean environments.   Once subjected to overload, overspeed, dusty/humid surroundings, poor lubrication or mounting misalignment, the actual service life will be drastically shortened. Therefore, selecting the right bearings, maintaining proper lubrication and stabilizing operating conditions are the fundamental ways to extend bearing service life. Ningbo Kent Bearing boosts efficiency via automated production lines, controls quality with precision inspection systems, and aligns dual standards with international norms. We deliver consistently reliable bearings featuring high precision, low noise and long service life, making us a preferred supplier of medium-to-high end motor bearings.