GRINDING MEDIA KNOWLEDGE
Grinding Ball Inventory: How to Set a Reorder Point
Plan grinding media replenishment using daily demand, actual lead time and safety stock, with a worked example and size-by-size inventory checks.
Track each specification separately
Record grinding ball inventory by diameter, material or grade, supplier and lot. A total of 100 tonnes does not prevent a shortage if the size required by the mill is unavailable; other sizes are not automatically interchangeable. Separate accepted stock from material awaiting inspection, quarantined stock and reserved quantities. Do not count unaccepted deliveries as usable inventory.
Use consistent time units for demand and lead time
Estimate daily demand from representative recent issue records and state whether the calculation uses calendar days or operating days. Replenishment lead time runs from ordering until accepted material is available for use, including production, inspection, transport and any necessary customs clearance. Convert lead time to operating days if demand is expressed per operating day. Plan initial charging after an overhaul and trial media separately so they do not distort routine top-up demand.
A worked reorder-point calculation
A simple model is: reorder point = average daily demand × replenishment lead time + safety stock. Inventory position = accepted stock on hand + confirmed incoming quantity − reserved demand. As an illustration only, demand of 2 tonnes/day, a 30-day lead time and 20 tonnes of safety stock give an 80-tonne reorder point. With 55 tonnes on hand, 30 incoming and 10 reserved, inventory position is 75 tonnes: start a replenishment review. This assumes consistent time units and on-time incoming deliveries.
Safety stock is not the order quantity
Safety stock covers variability in demand and delays; no fixed percentage suits every plant. Review historical delays, consumption variability, alternative supply and the consequences of downtime, then agree the buffer with production and purchasing. The reorder point indicates when to review; the order quantity also depends on demand until the next purchasing cycle, minimum order quantities, container loading, storage and working capital. An unconfirmed delivery estimate is not a firm arrival commitment.
Check timing weekly, then reconcile each receipt
For each specification, list available stock, future demand, the date each incoming lot should become usable and the person responsible for delivery risks. A projected negative balance before the next delivery signals a shortage even when total incoming tonnage looks sufficient. Update consumption and dates weekly and revisit assumptions when demand or lead time changes materially. On receipt, check specification, quantity and lot records, update acceptance status and close the relevant purchasing gap.
Information to include in an enquiry
Send the required specifications, expected monthly usage, current stock, required availability date and destination. Ask the supplier to distinguish production, inspection and transport schedules. Contact Zhang Tong: 15588869611@163.com; phone/WhatsApp: +86 155 8886 9611. This example explains planning and does not promise a particular lead time or supply capacity.