As a merchant, if the customer fails to sign the card after swiping it, the card swiping is unsuccessful or other reasons cause the funds to be unable to be credited into his account, the merchant can submit evidence to China UnionPay with the signature of the merchant stub to safeguard his rights and interests and prevent the customer or POS agent from cheating. At the same time, if the POS machine is blocked by the wind, it can also be used as evidence to request unsealing.
As a customer, if it is normal consumption, there is no mistake, and signing or not has no influence on yourself. However, it is recommended to keep the customer stub (no signature is required) for a period of time. Sometimes customers will be asked by the bank to upload proof materials.